Python Documentation contents — Python 3.14.3 documentation

Python Documentation contents¶ What’s New in Python What’s new in Python 3.14 Summary – Release highlights New features PEP 649 & PEP 749: Deferred evaluation of annotations PEP 734: Multiple interpreters in the standard library PEP 750: Template string literals PEP 768: Safe external debugger interface A new type of interpreter Free-threaded mode improvements Improved error messages PEP 784: Zstandard support in the standard library Asyncio introspection capabilities Concurrent safe warnings control Other language changes Built-ins Command line and environment PEP 758: Allow except and except* expressions without brackets PEP 765: Control flow in finally blocks Incremental garbage collection Default interactive shell New modules Improved modules argparse ast asyncio calendar concurrent.futures configparser contextvars ctypes curses datetime decimal difflib dis errno faulthandler fnmatch fractions functools getopt getpass graphlib heapq hmac http imaplib inspect io json linecache logging.handlers math mimetypes multiprocessing operator os os.path pathlib pdb pickle platform pydoc re socket ssl struct symtable sys sys.monitoring sysconfig tarfile threading tkinter turtle types typing unicodedata unittest urllib uuid webbrowser zipfile Optimizations asyncio base64 bdb difflib gc io pathlib pdb textwrap uuid zlib Removed argparse ast asyncio email importlib.abc itertools pathlib pkgutil pty sqlite3 urllib Deprecated New deprecations Pending removal in Python 3.15 Pending removal in Python 3.16 Pending removal in Python 3.17 Pending removal in Python 3.18 Pending removal in Python 3.19 Pending removal in future versions CPython bytecode changes Pseudo-instructions C API changes Python configuration C API New features in the C API Limited C API changes Removed C APIs Deprecated C APIs Pending removal in Python 3.15 Pending removal in Python 3.16 Pending removal in Python 3.18 Pending removal in future versions Build changes build-details.json Discontinuation of PGP signatures Free-threaded Python is officially supported Binary releases for the experimental just-in-time compiler Porting to Python 3.14 Changes in the Python API Changes in annotations (PEP 649 and PEP 749) Implications for annotated code Implications for readers of __annotations__ Related changes from __future__ import annotations Changes in the C API Notable changes in 3.14.1 What’s New In Python 3.13 Summary – Release Highlights New Features A better interactive interpreter Improved error messages Free-threaded CPython An experimental just-in-time (JIT) compiler Defined mutation semantics for locals() Support for mobile platforms Other Language Changes New Modules Improved Modules argparse array ast asyncio base64 compileall concurrent.futures configparser copy ctypes dbm dis doctest email enum fractions glob importlib io ipaddress itertools marshal math mimetypes mmap multiprocessing os os.path pathlib pdb queue random re shutil site sqlite3 ssl statistics subprocess sys tempfile time tkinter traceback types typing unicodedata venv warnings xml zipimport Optimizations Removed Modules And APIs PEP 594: Remove “dead batteries” from the standard library 2to3 builtins configparser importlib.metadata locale opcode optparse pathlib re tkinter.tix turtle typing unittest urllib webbrowser New Deprecations Pending removal in Python 3.14 Pending removal in Python 3.15 Pending removal in Python 3.16 Pending removal in Python 3.17 Pending removal in Python 3.18 Pending removal in Python 3.19 Pending removal in future versions CPython Bytecode Changes C API Changes New Features Changed C APIs Limited C API Changes Removed C APIs Deprecated C APIs Pending removal in Python 3.14 Pending removal in Python 3.15 Pending removal in Python 3.16 Pending removal in Python 3.18 Pending removal in future versions Build Changes Porting to Python 3.13 Changes in the Python API Changes in the C API Regression Test Changes What’s New In Python 3.12 Summary – Release highlights New Features PEP 695: Type Parameter Syntax PEP 701: Syntactic formalization of f-strings PEP 684: A Per-Interpreter GIL PEP 669: Low impact monitoring for CPython PEP 688: Making the buffer protocol accessible in Python PEP 709: Comprehension inlining Improved Error Messages New Features Related to Type Hints PEP 692: Using TypedDict for more precise **kwargs typing PEP 698: Override Decorator for Static Typing Other Language Changes New Modules Improved Modules array asyncio calendar csv dis fractions importlib.resources inspect itertools math os os.path pathlib platform pdb random shutil sqlite3 statistics sys tempfile threading tkinter tokenize types typing unicodedata unittest uuid Optimizations CPython bytecode changes Demos and Tools Deprecated Pending removal in Python 3.13 Pending removal in Python 3.14 Pending removal in Python 3.15 Pending removal in Python 3.16 Pending removal in Python 3.17 Pending removal in future versions Removed asynchat and asyncore configparser distutils ensurepip enum ftplib gzip hashlib importlib imp io locale smtpd sqlite3 ssl unittest webbrowser xml.etree.ElementTree zipimport Others Porting to Python 3.12 Changes in the Python API Build Changes C API Changes New Features Porting to Python 3.12 Deprecated Pending removal in Python 3.14 Pending removal in Python 3.15 Pending removal in Python 3.16 Pending removal in future versions Removed What’s New In Python 3.11 Summary – Release highlights New Features PEP 657: Fine-grained error locations in tracebacks PEP 654: Exception Groups and except* PEP 678: Exceptions can be enriched with notes Windows py.exe launcher improvements New Features Related to Type Hints PEP 646: Variadic generics PEP 655: Marking individual TypedDict items as required or not-required PEP 673: Self type PEP 675: Arbitrary literal string type PEP 681: Data class transforms PEP 563 may not be the future Other Language Changes Other CPython Implementation Changes New Modules Improved Modules asyncio contextlib dataclasses datetime enum fcntl fractions functools gzip hashlib IDLE and idlelib inspect locale logging math operator os pathlib re shutil socket sqlite3 string sys sysconfig tempfile threading time tkinter traceback typing unicodedata unittest venv warnings zipfile Optimizations Faster CPython Faster Startup Frozen imports / Static code objects Faster Runtime Cheaper, lazy Python frames Inlined Python function calls PEP 659: Specializing Adaptive Interpreter Misc FAQ How should I write my code to utilize these speedups? Will CPython 3.11 use more memory? I don’t see any speedups in my workload. Why? Is there a JIT compiler? About CPython bytecode changes New opcodes Replaced opcodes Changed/removed opcodes Deprecated Language/Builtins Modules Standard Library Pending Removal in Python 3.12 Removed Porting to Python 3.11 Build Changes C API Changes New Features Porting to Python 3.11 Deprecated Pending Removal in Python 3.12 Removed Notable changes in 3.11.4 tarfile Notable changes in 3.11.5 OpenSSL What’s New In Python 3.10 Summary – Release highlights New Features Parenthesized context managers Better error messages SyntaxErrors IndentationErrors AttributeErrors NameErrors PEP 626: Precise line numbers for debugging and other tools PEP 634: Structural Pattern Matching Syntax and operations Declarative approach Simple pattern: match to a literal Behavior without the wildcard Patterns with a literal and variable Patterns and classes Patterns with positional parameters Nested patterns Complex patterns and the wildcard Guard Other Key Features Optional EncodingWarning and encoding="locale" option New Features Related to Type Hints PEP 604: New Type Union Operator PEP 612: Parameter Specification Variables PEP 613: TypeAlias PEP 647: User-Defined Type Guards Other Language Changes New Modules Improved Modules asyncio argparse array asynchat, asyncore, smtpd base64 bdb bisect codecs collections.abc contextlib curses dataclasses __slots__ Keyword-only fields distutils doctest encodings enum fileinput faulthandler gc glob hashlib hmac IDLE and idlelib importlib.metadata inspect itertools linecache os os.path pathlib platform pprint py_compile pyclbr shelve statistics site socket ssl sqlite3 sys _thread threading traceback types typing unittest urllib.parse xml zipimport Optimizations Deprecated Removed Porting to Python 3.10 Changes in the Python syntax Changes in the Python API Changes in the C API CPython bytecode changes Build Changes C API Changes PEP 652: Maintaining the Stable ABI New Features Porting to Python 3.10 Deprecated Removed Notable security feature in 3.10.7 Notable security feature in 3.10.8 Notable changes in 3.10.12 tarfile What’s New In Python 3.9 Summary – Release highlights You should check for DeprecationWarning in your code New Features Dictionary Merge & Update Operators New String Methods to Remove Prefixes and Suffixes Type Hinting Generics in Standard Collections New Parser Other Language Changes New Modules zoneinfo graphlib Improved Modules ast asyncio compileall concurrent.futures curses datetime distutils fcntl ftplib gc hashlib http IDLE and idlelib imaplib importlib inspect ipaddress math multiprocessing nntplib os pathlib pdb poplib pprint pydoc random signal smtplib socket time sys tracemalloc typing unicodedata venv xml Optimizations Deprecated Removed Porting to Python 3.9 Changes in the Python API Changes in the C API CPython bytecode changes Build Changes C API Changes New Features Porting to Python 3.9 Removed Notable changes in Python 3.9.1 typing macOS 11.0 (Big Sur) and Apple Silicon Mac support Notable changes in Python 3.9.2 collections.abc urllib.parse Notable changes in Python 3.9.3 Notable changes in Python 3.9.5 urllib.parse Notable security feature in 3.9.14 Notable changes in 3.9.17 tarfile What’s New In Python 3.8 Summary – Release highlights New Features Assignment expressions Positional-only parameters Parallel filesystem cache for compiled bytecode files Debug build uses the same ABI as release build f-strings support = for self-documenting expressions and debugging PEP 578: Python Runtime Audit Hooks PEP 587: Python Initialization Configuration PEP 590: Vectorcall: a fast calling protocol for CPython Pickle protocol 5 with out-of-band data buffers Other Language Changes New Modules Improved Modules ast asyncio builtins collections cProfile csv curses ctypes datetime functools gc gettext gzip IDLE and idlelib inspect io itertools json.tool logging math mmap multiprocessing os os.path pathlib pickle plistlib pprint py_compile shlex shutil socket ssl statistics sys tarfile threading tokenize tkinter time typing unicodedata unittest venv weakref xml xmlrpc Optimizations Build and C API Changes Deprecated API and Feature Removals Porting to Python 3.8 Changes in Python behavior Changes in the Python API Changes in the C API CPython bytecode changes Demos and Tools Notable changes in Python 3.8.1 Notable changes in Python 3.8.2 Notable changes in Python 3.8.3 Notable changes in Python 3.8.8 Notable changes in Python 3.8.9 Notable changes in Python 3.8.10 macOS 11.0 (Big Sur) and Apple Silicon Mac support Notable changes in Python 3.8.10 urllib.parse Notable changes in Python 3.8.12 Changes in the Python API Notable security feature in 3.8.14 Notable changes in 3.8.17 tarfile What’s New In Python 3.7 Summary – Release Highlights New Features PEP 563: Postponed Evaluation of Annotations PEP 538: Legacy C Locale Coercion PEP 540: Forced UTF-8 Runtime Mode PEP 553: Built-in breakpoint() PEP 539: New C API for Thread-Local Storage PEP 562: Customization of Access to Module Attributes PEP 564: New Time Functions With Nanosecond Resolution PEP 565: Show DeprecationWarning in __main__ PEP 560: Core Support for typing module and Generic Types PEP 552: Hash-based .pyc Files PEP 545: Python Documentation Translations Python Development Mode (-X dev) Other Language Changes New Modules contextvars dataclasses importlib.resources Improved Modules argparse asyncio binascii calendar collections compileall concurrent.futures contextlib cProfile crypt datetime dbm decimal dis distutils enum functools gc hmac http.client http.server idlelib and IDLE importlib io ipaddress itertools locale logging math mimetypes msilib multiprocessing os pathlib pdb py_compile pydoc queue re signal socket socketserver sqlite3 ssl string subprocess sys time tkinter tracemalloc types unicodedata unittest unittest.mock urllib.parse uu uuid warnings xml xml.etree xmlrpc.server zipapp zipfile C API Changes Build Changes Optimizations Other CPython Implementation Changes Deprecated Python Behavior Deprecated Python modules, functions and methods aifc asyncio collections dbm enum gettext importlib locale macpath threading socket ssl sunau sys wave Deprecated functions and types of the C API Platform Support Removals API and Feature Removals Module Removals Windows-only Changes Porting to Python 3.7 Changes in Python Behavior Changes in the Python API Changes in the C API CPython bytecode changes Windows-only Changes Other CPython implementation changes Notable changes in Python 3.7.1 Notable changes in Python 3.7.2 Notable changes in Python 3.7.6 Notable changes in Python 3.7.10 Notable changes in Python 3.7.11 Notable security feature in 3.7.14 What’s New In Python 3.6 Summary – Release highlights New Features PEP 498: Formatted string literals PEP 526: Syntax for variable annotations PEP 515: Underscores in Numeric Literals PEP 525: Asynchronous Generators PEP 530: Asynchronous Comprehensions PEP 487: Simpler customization of class creation PEP 487: Descriptor Protocol Enhancements PEP 519: Adding a file system path protocol PEP 495: Local Time Disambiguation PEP 529: Change Windows filesystem encoding to UTF-8 PEP 528: Change Windows console encoding to UTF-8 PEP 520: Preserving Class Attribute Definition Order PEP 468: Preserving Keyword Argument Order New dict implementation PEP 523: Adding a frame evaluation API to CPython PYTHONMALLOC environment variable DTrace and SystemTap probing support Other Language Changes New Modules secrets Improved Modules array ast asyncio binascii cmath collections concurrent.futures contextlib datetime decimal distutils email encodings enum faulthandler fileinput hashlib http.client idlelib and IDLE importlib inspect json logging math multiprocessing os pathlib pdb pickle pickletools pydoc random re readline rlcompleter shlex site sqlite3 socket socketserver ssl statistics struct subprocess sys telnetlib time timeit tkinter traceback tracemalloc typing unicodedata unittest.mock urllib.request urllib.robotparser venv warnings winreg winsound xmlrpc.client zipfile zlib Optimizations Build and C API Changes Other Improvements Deprecated New Keywords Deprecated Python behavior Deprecated Python modules, functions and methods asynchat asyncore dbm distutils grp importlib os re ssl tkinter venv xml Deprecated functions and types of the C API Deprecated Build Options Removed API and Feature Removals Porting to Python 3.6 Changes in ‘python’ Command Behavior Changes in the Python API Changes in the C API CPython bytecode changes Notable changes in Python 3.6.2 New make regen-all build target Removal of make touch build target Notable changes in Python 3.6.4 Notable changes in Python 3.6.5 Notable changes in Python 3.6.7 Notable changes in Python 3.6.10 Notable changes in Python 3.6.13 Notable changes in Python 3.6.14 What’s New In Python 3.5 Summary – Release highlights New Features PEP 492 - Coroutines with async and await syntax PEP 465 - A dedicated infix operator for matrix multiplication PEP 448 - Additional Unpacking Generalizations PEP 461 - percent formatting support for bytes and bytearray PEP 484 - Type Hints PEP 471 - os.scandir() function – a better and faster directory iterator PEP 475: Retry system calls failing with EINTR PEP 479: Change StopIteration handling inside generators PEP 485: A function for testing approximate equality PEP 486: Make the Python Launcher aware of virtual environments PEP 488: Elimination of PYO files PEP 489: Multi-phase extension module initialization Other Language Changes New Modules typing zipapp Improved Modules argparse asyncio bz2 cgi cmath code collections collections.abc compileall concurrent.futures configparser contextlib csv curses dbm difflib distutils doctest email enum faulthandler functools glob gzip heapq http http.client idlelib and IDLE imaplib imghdr importlib inspect io ipaddress json linecache locale logging lzma math multiprocessing operator os pathlib pickle poplib re readline selectors shutil signal smtpd smtplib sndhdr socket ssl Memory BIO Support Application-Layer Protocol Negotiation Support Other Changes sqlite3 subprocess sys sysconfig tarfile threading time timeit tkinter traceback types unicodedata unittest unittest.mock urllib wsgiref xmlrpc xml.sax zipfile Other module-level changes Optimizations Build and C API Changes Deprecated New Keywords Deprecated Python Behavior Unsupported Operating Systems Deprecated Python modules, functions and methods Removed API and Feature Removals Porting to Python 3.5 Changes in Python behavior Changes in the Python API Changes in the C API Notable changes in Python 3.5.4 New make regen-all build target Removal of make touch build target What’s New In Python 3.4 Summary – Release Highlights New Features PEP 453: Explicit Bootstrapping of PIP in Python Installations Bootstrapping pip By Default Documentation Changes PEP 446: Newly Created File Descriptors Are Non-Inheritable Improvements to Codec Handling PEP 451: A ModuleSpec Type for the Import System Other Language Changes New Modules asyncio ensurepip enum pathlib selectors statistics tracemalloc Improved Modules abc aifc argparse audioop base64 collections colorsys contextlib dbm dis doctest email filecmp functools gc glob hashlib hmac html http idlelib and IDLE importlib inspect ipaddress logging marshal mmap multiprocessing operator os pdb pickle plistlib poplib pprint pty pydoc re resource select shelve shutil smtpd smtplib socket sqlite3 ssl stat struct subprocess sunau sys tarfile textwrap threading traceback types urllib unittest venv wave weakref xml.etree zipfile CPython Implementation Changes PEP 445: Customization of CPython Memory Allocators PEP 442: Safe Object Finalization PEP 456: Secure and Interchangeable Hash Algorithm PEP 436: Argument Clinic Other Build and C API Changes Other Improvements Significant Optimizations Deprecated Deprecations in the Python API Deprecated Features Removed Operating Systems No Longer Supported API and Feature Removals Code Cleanups Porting to Python 3.4 Changes in ‘python’ Command Behavior Changes in the Python API Changes in the C API Changed in 3.4.3 PEP 476: Enabling certificate verification by default for stdlib http clients What’s New In Python 3.3 Summary – Release highlights PEP 405: Virtual Environments PEP 420: Implicit Namespace Packages PEP 3118: New memoryview implementation and buffer protocol documentation Features API changes PEP 393: Flexible String Representation Functionality Performance and resource usage PEP 397: Python Launcher for Windows PEP 3151: Reworking the OS and IO exception hierarchy PEP 380: Syntax for Delegating to a Subgenerator PEP 409: Suppressing exception context PEP 414: Explicit Unicode literals PEP 3155: Qualified name for classes and functions PEP 412: Key-Sharing Dictionary PEP 362: Function Signature Object PEP 421: Adding sys.implementation SimpleNamespace Using importlib as the Implementation of Import New APIs Visible Changes Other Language Changes A Finer-Grained Import Lock Builtin functions and types New Modules faulthandler ipaddress lzma Improved Modules abc array base64 binascii bz2 codecs collections contextlib crypt curses datetime decimal Features API changes email Policy Framework Provisional Policy with New Header API Other API Changes ftplib functools gc hmac http html imaplib inspect io itertools logging math mmap multiprocessing nntplib os pdb pickle pydoc re sched select shlex shutil signal smtpd smtplib socket socketserver sqlite3 ssl stat struct subprocess sys tarfile tempfile textwrap threading time types unittest urllib webbrowser xml.etree.ElementTree zlib Optimizations Build and C API Changes Deprecated Unsupported Operating Systems Deprecated Python modules, functions and methods Deprecated functions and types of the C API Deprecated features Porting to Python 3.3 Porting Python code Porting C code Building C extensions Command Line Switch Changes What’s New In Python 3.2 PEP 384: Defining a Stable ABI PEP 389: Argparse Command Line Parsing Module PEP 391: Dictionary Based Configuration for Logging PEP 3148: The concurrent.futures module PEP 3147: PYC Repository Directories PEP 3149: ABI Version Tagged .so Files PEP 3333: Python Web Server Gateway Interface v1.0.1 Other Language Changes New, Improved, and Deprecated Modules email elementtree functools itertools collections threading datetime and time math abc io reprlib logging csv contextlib decimal and fractions ftp popen select gzip and zipfile tarfile hashlib ast os shutil sqlite3 html socket ssl nntp certificates imaplib http.client unittest random poplib asyncore tempfile inspect pydoc dis dbm ctypes site sysconfig pdb configparser urllib.parse mailbox turtledemo Multi-threading Optimizations Unicode Codecs Documentation IDLE Code Repository Build and C API Changes Porting to Python 3.2 What’s New In Python 3.1 PEP 372: Ordered Dictionaries PEP 378: Format Specifier for Thousands Separator Other Language Changes New, Improved, and Deprecated Modules Optimizations IDLE Build and C API Changes Porting to Python 3.1 What’s New In Python 3.0 Common Stumbling Blocks Print Is A Function Views And Iterators Instead Of Lists Ordering Comparisons Integers Text Vs. Data Instead Of Unicode Vs. 8-bit Overview Of Syntax Changes New Syntax Changed Syntax Removed Syntax Changes Already Present In Python 2.6 Library Changes PEP 3101: A New Approach To String Formatting Changes To Exceptions Miscellaneous Other Changes Operators And Special Methods Builtins Build and C API Changes Performance Porting To Python 3.0 What’s New in Python 2.7 The Future for Python 2.x Changes to the Handling of Deprecation Warnings Python 3.1 Features PEP 372: Adding an Ordered Dictionary to collections PEP 378: Format Specifier for Thousands Separator PEP 389: The argparse Module for Parsing Command Lines PEP 391: Dictionary-Based Configuration For Logging PEP 3106: Dictionary Views PEP 3137: The memoryview Object Other Language Changes Interpreter Changes Optimizations New and Improved Modules New module: importlib New module: sysconfig ttk: Themed Widgets for Tk Updated module: unittest Updated module: ElementTree 1.3 Build and C API Changes Capsules Port-Specific Changes: Windows Port-Specific Changes: Mac OS X Port-Specific Changes: FreeBSD Other Changes and Fixes Porting to Python 2.7 New Features Added to Python 2.7 Maintenance Releases Two new environment variables for debug mode PEP 434: IDLE Enhancement Exception for All Branches PEP 466: Network Security Enhancements for Python 2.7 PEP 477: Backport ensurepip (PEP 453) to Python 2.7 Bootstrapping pip By Default Documentation Changes PEP 476: Enabling certificate verification by default for stdlib http clients PEP 493: HTTPS verification migration tools for Python 2.7 New make regen-all build target Removal of make touch build target Acknowledgements What’s New in Python 2.6 Python 3.0 Changes to the Development Process New Issue Tracker: Roundup New Documentation Format: reStructuredText Using Sphinx PEP 343: The ‘with’ statement Writing Context Managers The contextlib module PEP 366: Explicit Relative Imports From a Main Module PEP 370: Per-user site-packages Directory PEP 371: The multiprocessing Package PEP 3101: Advanced String Formatting PEP 3105: print As a Function PEP 3110: Exception-Handling Changes PEP 3112: Byte Literals PEP 3116: New I/O Library PEP 3118: Revised Buffer Protocol PEP 3119: Abstract Base Classes PEP 3127: Integer Literal Support and Syntax PEP 3129: Class Decorators PEP 3141: A Type Hierarchy for Numbers The fractions Module Other Language Changes Optimizations Interpreter Changes New and Improved Modules The ast module The future_builtins module The json module: JavaScript Object Notation The plistlib module: A Property-List Parser ctypes Enhancements Improved SSL Support Deprecations and Removals Build and C API Changes Port-Specific Changes: Windows Port-Specific Changes: Mac OS X Port-Specific Changes: IRIX Porting to Python 2.6 Acknowledgements What’s New in Python 2.5 PEP 308: Conditional Expressions PEP 309: Partial Function Application PEP 314: Metadata for Python Software Packages v1.1 PEP 328: Absolute and Relative Imports PEP 338: Executing Modules as Scripts PEP 341: Unified try/except/finally PEP 342: New Generator Features PEP 343: The ‘with’ statement Writing Context Managers The contextlib module PEP 352: Exceptions as New-Style Classes PEP 353: Using ssize_t as the index type PEP 357: The ‘__index__’ method Other Language Changes Interactive Interpreter Changes Optimizations New, Improved, and Removed Modules The ctypes package The ElementTree package The hashlib package The sqlite3 package The wsgiref package Build and C API Changes Port-Specific Changes Porting to Python 2.5 Acknowledgements What’s New in Python 2.4 PEP 218: Built-In Set Objects PEP 237: Unifying Long Integers and Integers PEP 289: Generator Expressions PEP 292: Simpler String Substitutions PEP 318: Decorators for Functions and Methods PEP 322: Reverse Iteration PEP 324: New subprocess Module PEP 327: Decimal Data Type Why is Decimal needed? The Decimal type The Context type PEP 328: Multi-line Imports PEP 331: Locale-Independent Float/String Conversions Other Language Changes Optimizations New, Improved, and Deprecated Modules cookielib doctest Build and C API Changes Port-Specific Changes Porting to Python 2.4 Acknowledgements What’s New in Python 2.3 PEP 218: A Standard Set Datatype PEP 255: Simple Generators PEP 263: Source Code Encodings PEP 273: Importing Modules from ZIP Archives PEP 277: Unicode file name support for Windows NT PEP 278: Universal Newline Support PEP 279: enumerate() PEP 282: The logging Package PEP 285: A Boolean Type PEP 293: Codec Error Handling Callbacks PEP 301: Package Index and Metadata for Distutils PEP 302: New Import Hooks PEP 305: Comma-separated Files PEP 307: Pickle Enhancements Extended Slices Other Language Changes String Changes Optimizations New, Improved, and Deprecated Modules Date/Time Type The optparse Module Pymalloc: A Specialized Object Allocator Build and C API Changes Port-Specific Changes Other Changes and Fixes Porting to Python 2.3 Acknowledgements What’s New in Python 2.2 Introduction PEPs 252 and 253: Type and Class Changes Old and New Classes Descriptors Multiple Inheritance: The Diamond Rule Attribute Access Related Links PEP 234: Iterators PEP 255: Simple Generators PEP 237: Unifying Long Integers and Integers PEP 238: Changing the Division Operator Unicode Changes PEP 227: Nested Scopes New and Improved Modules Interpreter Changes and Fixes Other Changes and Fixes Acknowledgements What’s New in Python 2.1 Introduction PEP 227: Nested Scopes PEP 236: __future__ Directives PEP 207: Rich Comparisons PEP 230: Warning Framework PEP 229: New Build System PEP 205: Weak References PEP 232: Function Attributes PEP 235: Importing Modules on Case-Insensitive Platforms PEP 217: Interactive Display Hook PEP 208: New Coercion Model PEP 241: Metadata in Python Packages New and Improved Modules Other Changes and Fixes Acknowledgements What’s New in Python 2.0 Introduction What About Python 1.6? New Development Process Unicode List Comprehensions Augmented Assignment String Methods Garbage Collection of Cycles Other Core Changes Minor Language Changes Changes to Built-in Functions Porting to 2.0 Extending/Embedding Changes Distutils: Making Modules Easy to Install XML Modules SAX2 Support DOM Support Relationship to PyXML Module changes New modules IDLE Improvements Deleted and Deprecated Modules Acknowledgements Changelog Python next macOS Windows Library Documentation Core and Builtins Python 3.14.3 final Windows Tools/Demos Tests Security Library IDLE Documentation Core and Builtins C API Build Python 3.14.2 final Security Library Core and Builtins Library Python 3.14.1 final Windows Tools/Demos Tests Security Library IDLE Documentation Core and Builtins Library Core and Builtins Library Core and Builtins Library Core and Builtins Library Core and Builtins Library Core and Builtins Library Core and Builtins C API Build Python 3.14.0 final macOS Windows Tools/Demos Security Library Python 3.14.0 release candidate 3 Windows Tools/Demos Security Library Core and Builtins Python 3.14.0 release candidate 2 macOS Windows Library Documentation Core and Builtins C API Build Python 3.14.0 release candidate 1 Tools/Demos Security Library Core and Builtins Library Core and Builtins Library Core and Builtins C API Build Python 3.14.0 beta 4 Tools/Demos Tests Security Library Documentation Core and Builtins C API Build Python 3.14.0 beta 3 Windows Tests Security Library Documentation Core and Builtins Library Core and Builtins Library Core and Builtins Library Core and Builtins C API Build Python 3.14.0 beta 2 Windows Tools/Demos Tests Security Library Core and Builtins C API Build Python 3.14.0 beta 1 Windows Tools/Demos Tests Security Library IDLE Documentation Core and Builtins Library Core and Builtins Library Core and Builtins Library C API Build Python 3.14.0 alpha 7 macOS Windows Tools/Demos Tests Security Library Documentation Core and Builtins Library Core 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Whetting Your Appetite 2. Using the Python Interpreter 2.1. Invoking the Interpreter 2.1.1. Argument Passing 2.1.2. Interactive Mode 2.2. The Interpreter and Its Environment 2.2.1. Source Code Encoding 3. An Informal Introduction to Python 3.1. Using Python as a Calculator 3.1.1. Numbers 3.1.2. Text 3.1.3. Lists 3.2. First Steps Towards Programming 4. More Control Flow Tools 4.1. if Statements 4.2. for Statements 4.3. The range() Function 4.4. break and continue Statements 4.5. else Clauses on Loops 4.6. pass Statements 4.7. match Statements 4.8. Defining Functions 4.9. More on Defining Functions 4.9.1. Default Argument Values 4.9.2. Keyword Arguments 4.9.3. Special parameters 4.9.3.1. Positional-or-Keyword Arguments 4.9.3.2. Positional-Only Parameters 4.9.3.3. Keyword-Only Arguments 4.9.3.4. Function Examples 4.9.3.5. Recap 4.9.4. Arbitrary Argument Lists 4.9.5. Unpacking Argument Lists 4.9.6. Lambda Expressions 4.9.7. Documentation Strings 4.9.8. Function Annotations 4.10. Intermezzo: Coding Style 5. Data Structures 5.1. More on Lists 5.1.1. Using Lists as Stacks 5.1.2. Using Lists as Queues 5.1.3. List Comprehensions 5.1.4. Nested List Comprehensions 5.2. The del statement 5.3. Tuples and Sequences 5.4. Sets 5.5. Dictionaries 5.6. Looping Techniques 5.7. More on Conditions 5.8. Comparing Sequences and Other Types 6. Modules 6.1. More on Modules 6.1.1. Executing modules as scripts 6.1.2. The Module Search Path 6.1.3. “Compiled” Python files 6.2. Standard Modules 6.3. The dir() Function 6.4. Packages 6.4.1. Importing * From a Package 6.4.2. Intra-package References 6.4.3. Packages in Multiple Directories 7. Input and Output 7.1. Fancier Output Formatting 7.1.1. Formatted String Literals 7.1.2. The String format() Method 7.1.3. Manual String Formatting 7.1.4. Old string formatting 7.2. Reading and Writing Files 7.2.1. Methods of File Objects 7.2.2. Saving structured data with json 8. Errors and Exceptions 8.1. Syntax Errors 8.2. Exceptions 8.3. Handling Exceptions 8.4. Raising Exceptions 8.5. Exception Chaining 8.6. User-defined Exceptions 8.7. Defining Clean-up Actions 8.8. Predefined Clean-up Actions 8.9. Raising and Handling Multiple Unrelated Exceptions 8.10. Enriching Exceptions with Notes 9. Classes 9.1. A Word About Names and Objects 9.2. Python Scopes and Namespaces 9.2.1. Scopes and Namespaces Example 9.3. A First Look at Classes 9.3.1. Class Definition Syntax 9.3.2. Class Objects 9.3.3. Instance Objects 9.3.4. Method Objects 9.3.5. Class and Instance Variables 9.4. Random Remarks 9.5. Inheritance 9.5.1. Multiple Inheritance 9.6. Private Variables 9.7. Odds and Ends 9.8. Iterators 9.9. Generators 9.10. Generator Expressions 10. Brief Tour of the Standard Library 10.1. Operating System Interface 10.2. File Wildcards 10.3. Command Line Arguments 10.4. Error Output Redirection and Program Termination 10.5. String Pattern Matching 10.6. Mathematics 10.7. Internet Access 10.8. Dates and Times 10.9. Data Compression 10.10. Performance Measurement 10.11. Quality Control 10.12. Batteries Included 11. Brief Tour of the Standard Library — Part II 11.1. Output Formatting 11.2. Templating 11.3. Working with Binary Data Record Layouts 11.4. Multi-threading 11.5. Logging 11.6. Weak References 11.7. Tools for Working with Lists 11.8. Decimal Floating-Point Arithmetic 12. Virtual Environments and Packages 12.1. Introduction 12.2. Creating Virtual Environments 12.3. Managing Packages with pip 13. What Now? 14. Interactive Input Editing and History Substitution 14.1. Tab Completion and History Editing 14.2. Alternatives to the Interactive Interpreter 15. Floating-Point Arithmetic: Issues and Limitations 15.1. Representation Error 16. Appendix 16.1. Interactive Mode 16.1.1. Error Handling 16.1.2. Executable Python Scripts 16.1.3. The Interactive Startup File 16.1.4. The Customization Modules Python Setup and Usage 1. Command line and environment 1.1. Command line 1.1.1. Interface options 1.1.2. Generic options 1.1.3. Miscellaneous options 1.1.4. Controlling color 1.2. Environment variables 1.2.1. Debug-mode variables 2. Using Python on Unix platforms 2.1. Getting and installing the latest version of Python 2.1.1. On Linux 2.1.1.1. Installing IDLE 2.1.2. On FreeBSD and OpenBSD 2.2. Building Python 2.3. Python-related paths and files 2.4. Miscellaneous 2.5. Custom OpenSSL 3. Configure Python 3.1. Build Requirements 3.1.1. Requirements for optional modules 3.2. Generated files 3.2.1. configure script 3.3. Configure Options 3.3.1. General Options 3.3.2. C compiler options 3.3.3. Linker options 3.3.4. Options for third-party dependencies 3.3.5. WebAssembly Options 3.3.6. Install Options 3.3.7. Performance options 3.3.8. Python Debug Build 3.3.9. Debug options 3.3.10. Linker options 3.3.11. Libraries options 3.3.12. Security Options 3.3.13. macOS Options 3.3.14. iOS Options 3.3.15. Cross Compiling Options 3.4. Python Build System 3.4.1. Main files of the build system 3.4.2. Main build steps 3.4.3. Main Makefile targets 3.4.3.1. make 3.4.3.2. make platform 3.4.3.3. make profile-opt 3.4.3.4. make clean 3.4.3.5. make distclean 3.4.3.6. make install 3.4.3.7. make test 3.4.3.8. make ci 3.4.3.9. make buildbottest 3.4.3.10. make regen-all 3.4.4. C extensions 3.5. Compiler and linker flags 3.5.1. Preprocessor flags 3.5.2. Compiler flags 3.5.3. Linker flags 4. Using Python on Windows 4.1. Python install manager 4.1.1. Installation 4.1.2. Basic use 4.1.3. Command help 4.1.4. Listing runtimes 4.1.5. Installing runtimes 4.1.6. Offline installs 4.1.7. Uninstalling runtimes 4.1.8. Configuration 4.1.9. Shebang lines 4.1.10. Advanced installation 4.1.11. Administrative configuration 4.1.12. Installing free-threaded binaries 4.1.13. Troubleshooting 4.2. The embeddable package 4.2.1. Python application 4.2.2. Embedding Python 4.3. The nuget.org packages 4.3.1. Free-threaded packages 4.4. Alternative bundles 4.5. Supported Windows versions 4.6. Removing the MAX_PATH limitation 4.7. UTF-8 mode 4.8. Finding modules 4.9. Additional modules 4.9.1. PyWin32 4.9.2. cx_Freeze 4.10. Compiling Python on Windows 4.11. The full installer (deprecated) 4.11.1. Installation steps 4.11.2. Removing the MAX_PATH limitation 4.11.3. Installing without UI 4.11.4. Installing without downloading 4.11.5. Modifying an install 4.11.6. Installing free-threaded binaries 4.12. Python launcher for Windows (deprecated) 4.12.1. Getting started 4.12.1.1. From the command-line 4.12.1.2. Virtual environments 4.12.1.3. From a script 4.12.1.4. From file associations 4.12.2. Shebang lines 4.12.3. Arguments in shebang lines 4.12.4. Customization 4.12.4.1. Customization via INI files 4.12.4.2. Customizing default Python versions 4.12.5. Diagnostics 4.12.6. Dry run 4.12.7. Install on demand 4.12.8. Return codes 5. Using Python on macOS 5.1. Using Python for macOS from python.org 5.1.1. Installation steps 5.1.2. How to run a Python script 5.2. Alternative Distributions 5.3. Installing Additional Python Packages 5.4. GUI Programming 5.5. Advanced Topics 5.5.1. Installing Free-threaded Binaries 5.5.2. Installing using the command line 5.5.3. Distributing Python Applications 5.5.4. App Store Compliance 5.6. Other Resources 6. Using Python on Android 6.1. Adding Python to an Android app 6.2. Building a Python package for Android 7. Using Python on iOS 7.1. Python at runtime on iOS 7.1.1. iOS version compatibility 7.1.2. Platform identification 7.1.3. Standard library availability 7.1.4. Binary extension modules 7.1.5. Compiler stub binaries 7.2. Installing Python on iOS 7.2.1. Tools for building iOS apps 7.2.2. Adding Python to an iOS project 7.2.3. Testing a Python package 7.3. App Store Compliance 7.3.1. Incompatible code in the standard library 7.3.2. Privacy manifests 8. Editors and IDEs 8.1. IDLE — Python editor and shell 8.2. Other Editors and IDEs The Python Language Reference 1. Introduction 1.1. Alternate Implementations 1.2. Notation 1.2.1. Lexical and Syntactic definitions 2. Lexical analysis 2.1. Line structure 2.1.1. Logical lines 2.1.2. Physical lines 2.1.3. Comments 2.1.4. Encoding declarations 2.1.5. Explicit line joining 2.1.6. Implicit line joining 2.1.7. Blank lines 2.1.8. Indentation 2.1.9. Whitespace between tokens 2.1.10. End marker 2.2. Other tokens 2.3. Names (identifiers and keywords) 2.3.1. Keywords 2.3.2. Soft Keywords 2.3.3. Reserved classes of identifiers 2.3.4. Non-ASCII characters in names 2.4. Literals 2.5. String and Bytes literals 2.5.1. Triple-quoted strings 2.5.2. String prefixes 2.5.3. Formal grammar 2.5.4. Escape sequences 2.5.4.1. Ignored end of line 2.5.4.2. Escaped characters 2.5.4.3. Octal character 2.5.4.4. Hexadecimal character 2.5.4.5. Named Unicode character 2.5.4.6. Hexadecimal Unicode characters 2.5.4.7. Unrecognized escape sequences 2.5.5. Bytes literals 2.5.6. Raw string literals 2.5.7. f-strings 2.5.8. t-strings 2.5.9. Formal grammar for f-strings 2.6. Numeric literals 2.6.1. Integer literals 2.6.2. Floating-point literals 2.6.3. Imaginary literals 2.7. Operators and delimiters 3. Data model 3.1. Objects, values and types 3.2. The standard type hierarchy 3.2.1. None 3.2.2. NotImplemented 3.2.3. Ellipsis 3.2.4. numbers.Number 3.2.4.1. numbers.Integral 3.2.4.2. numbers.Real (float) 3.2.4.3. numbers.Complex (complex) 3.2.5. Sequences 3.2.5.1. Immutable sequences 3.2.5.2. Mutable sequences 3.2.6. Set types 3.2.7. Mappings 3.2.7.1. Dictionaries 3.2.8. Callable types 3.2.8.1. User-defined functions 3.2.8.1.1. Special read-only attributes 3.2.8.1.2. Special writable attributes 3.2.8.2. Instance methods 3.2.8.3. Generator functions 3.2.8.4. Coroutine functions 3.2.8.5. Asynchronous generator functions 3.2.8.6. Built-in functions 3.2.8.7. Built-in methods 3.2.8.8. Classes 3.2.8.9. Class Instances 3.2.9. Modules 3.2.9.1. Import-related attributes on module objects 3.2.9.2. Other writable attributes on module objects 3.2.9.3. Module dictionaries 3.2.10. Custom classes 3.2.10.1. Special attributes 3.2.10.2. Special methods 3.2.11. Class instances 3.2.11.1. Special attributes 3.2.12. I/O objects (also known as file objects) 3.2.13. Internal types 3.2.13.1. Code objects 3.2.13.1.1. Special read-only attributes 3.2.13.1.2. Methods on code objects 3.2.13.2. Frame objects 3.2.13.2.1. Special read-only attributes 3.2.13.2.2. Special writable attributes 3.2.13.2.3. Frame object methods 3.2.13.3. Traceback objects 3.2.13.4. Slice objects 3.2.13.5. Static method objects 3.2.13.6. Class method objects 3.3. Special method names 3.3.1. Basic customization 3.3.2. Customizing attribute access 3.3.2.1. Customizing module attribute access 3.3.2.2. Implementing Descriptors 3.3.2.3. Invoking Descriptors 3.3.2.4. __slots__ 3.3.3. Customizing class creation 3.3.3.1. Metaclasses 3.3.3.2. Resolving MRO entries 3.3.3.3. Determining the appropriate metaclass 3.3.3.4. Preparing the class namespace 3.3.3.5. Executing the class body 3.3.3.6. Creating the class object 3.3.3.7. Uses for metaclasses 3.3.4. Customizing instance and subclass checks 3.3.5. Emulating generic types 3.3.5.1. The purpose of __class_getitem__ 3.3.5.2. __class_getitem__ versus __getitem__ 3.3.6. Emulating callable objects 3.3.7. Emulating container types 3.3.8. Emulating numeric types 3.3.9. With Statement Context Managers 3.3.10. Customizing positional arguments in class pattern matching 3.3.11. Emulating buffer types 3.3.12. Annotations 3.3.13. Special method lookup 3.4. Coroutines 3.4.1. Awaitable Objects 3.4.2. Coroutine Objects 3.4.3. Asynchronous Iterators 3.4.4. Asynchronous Context Managers 4. Execution model 4.1. Structure of a program 4.2. Naming and binding 4.2.1. Binding of names 4.2.2. Resolution of names 4.2.3. Annotation scopes 4.2.4. Lazy evaluation 4.2.5. Builtins and restricted execution 4.2.6. Interaction with dynamic features 4.3. Exceptions 4.4. Runtime Components 4.4.1. General Computing Model 4.4.2. Python Runtime Model 5. The import system 5.1. importlib 5.2. Packages 5.2.1. Regular packages 5.2.2. Namespace packages 5.3. Searching 5.3.1. The module cache 5.3.2. Finders and loaders 5.3.3. Import hooks 5.3.4. The meta path 5.4. Loading 5.4.1. Loaders 5.4.2. Submodules 5.4.3. Module specs 5.4.4. __path__ attributes on modules 5.4.5. Module reprs 5.4.6. Cached bytecode invalidation 5.5. The Path Based Finder 5.5.1. Path entry finders 5.5.2. Path entry finder protocol 5.6. Replacing the standard import system 5.7. Package Relative Imports 5.8. Special considerations for __main__ 5.8.1. __main__.__spec__ 5.9. References 6. Expressions 6.1. Arithmetic conversions 6.2. Atoms 6.2.1. Built-in constants 6.2.2. Identifiers (Names) 6.2.2.1. Private name mangling 6.2.3. Literals 6.2.3.1. Literals and object identity 6.2.3.2. String literal concatenation 6.2.4. Parenthesized forms 6.2.5. Displays for lists, sets and dictionaries 6.2.6. List displays 6.2.7. Set displays 6.2.8. Dictionary displays 6.2.9. Generator expressions 6.2.10. Yield expressions 6.2.10.1. Generator-iterator methods 6.2.10.2. Examples 6.2.10.3. Asynchronous generator functions 6.2.10.4. Asynchronous generator-iterator methods 6.3. Primaries 6.3.1. Attribute references 6.3.2. Subscriptions and slicings 6.3.2.1. Slicings 6.3.2.2. Comma-separated subscripts 6.3.2.3. “Starred” subscriptions 6.3.2.4. Formal subscription grammar 6.3.3. Calls 6.4. Await expression 6.5. The power operator 6.6. Unary arithmetic and bitwise operations 6.7. Binary arithmetic operations 6.8. Shifting operations 6.9. Binary bitwise operations 6.10. Comparisons 6.10.1. Value comparisons 6.10.2. Membership test operations 6.10.3. Identity comparisons 6.11. Boolean operations 6.12. Assignment expressions 6.13. Conditional expressions 6.14. Lambdas 6.15. Expression lists 6.16. Evaluation order 6.17. Operator precedence 7. Simple statements 7.1. Expression statements 7.2. Assignment statements 7.2.1. Augmented assignment statements 7.2.2. Annotated assignment statements 7.3. The assert statement 7.4. The pass statement 7.5. The del statement 7.6. The return statement 7.7. The yield statement 7.8. The raise statement 7.9. The break statement 7.10. The continue statement 7.11. The import statement 7.11.1. Future statements 7.12. The global statement 7.13. The nonlocal statement 7.14. The type statement 8. Compound statements 8.1. The if statement 8.2. The while statement 8.3. The for statement 8.4. The try statement 8.4.1. except clause 8.4.2. except* clause 8.4.3. else clause 8.4.4. finally clause 8.5. The with statement 8.6. The match statement 8.6.1. Overview 8.6.2. Guards 8.6.3. Irrefutable Case Blocks 8.6.4. Patterns 8.6.4.1. OR Patterns 8.6.4.2. AS Patterns 8.6.4.3. Literal Patterns 8.6.4.4. Capture Patterns 8.6.4.5. Wildcard Patterns 8.6.4.6. Value Patterns 8.6.4.7. Group Patterns 8.6.4.8. Sequence Patterns 8.6.4.9. Mapping Patterns 8.6.4.10. Class Patterns 8.7. Function definitions 8.8. Class definitions 8.9. Coroutines 8.9.1. Coroutine function definition 8.9.2. The async for statement 8.9.3. The async with statement 8.10. Type parameter lists 8.10.1. Generic functions 8.10.2. Generic classes 8.10.3. Generic type aliases 8.11. Annotations 9. Top-level components 9.1. Complete Python programs 9.2. File input 9.3. Interactive input 9.4. Expression input 10. Full Grammar specification The Python Standard Library Introduction Notes on availability WebAssembly platforms Mobile platforms Built-in Functions Built-in Constants Constants added by the site module Built-in Types Truth Value Testing Boolean Operations — and, or, not Comparisons Numeric Types — int, float, complex Bitwise Operations on Integer Types Additional Methods on Integer Types Additional Methods on Float Additional Methods on Complex Hashing of numeric types Boolean Type - bool Iterator Types Generator Types Sequence Types — list, tuple, range Common Sequence Operations Immutable Sequence Types Mutable Sequence Types Lists Tuples Ranges Text and Binary Sequence Type Methods Summary Text Sequence Type — str String Methods Formatted String Literals (f-strings) Debug specifier Conversion specifier Format specifier Template String Literals (t-strings) printf-style String Formatting Binary Sequence Types — bytes, bytearray, memoryview Bytes Objects Bytearray Objects Bytes and Bytearray Operations printf-style Bytes Formatting Memory Views Set Types — set, frozenset Mapping Types — dict Dictionary view objects Context Manager Types Type Annotation Types — Generic Alias, Union Generic Alias Type Standard Generic Classes Special Attributes of GenericAlias objects Union Type Other Built-in Types Modules Classes and Class Instances Functions Methods Code Objects Type Objects The Null Object The Ellipsis Object The NotImplemented Object Internal Objects Special Attributes Integer string conversion length limitation Affected APIs Configuring the limit Recommended configuration Built-in Exceptions Exception context Inheriting from built-in exceptions Base classes Concrete exceptions OS exceptions Warnings Exception groups Exception hierarchy Thread Safety Guarantees Thread safety for list objects Thread safety for dict objects Text Processing Services string — Common string operations String constants Custom String Formatting Format String Syntax Format Specification Mini-Language Format examples Template strings ($-strings) Helper functions string.templatelib — Support for template string literals Template strings Types Helper functions re — Regular expression operations Regular Expression Syntax Module Contents Flags Functions Exceptions Regular Expression Objects Match Objects Regular Expression Examples Checking for a Pair Simulating scanf() search() vs. match() Making a Phonebook Text Munging Finding all Adverbs Finding all Adverbs and their Positions Raw String Notation Writing a Tokenizer difflib — Helpers for computing deltas SequenceMatcher Objects SequenceMatcher Examples Differ Objects Differ Example A command-line interface to difflib ndiff example textwrap — Text wrapping and filling unicodedata — Unicode Database stringprep — Internet String Preparation readline — GNU readline interface Init file Line buffer History file History list Startup hooks Completion Example rlcompleter — Completion function for GNU readline Binary Data Services struct — Interpret bytes as packed binary data Functions and Exceptions Format Strings Byte Order, Size, and Alignment Format Characters Examples Applications Native Formats Standard Formats Classes codecs — Codec registry and base classes Codec Base Classes Error Handlers Stateless Encoding and Decoding Incremental Encoding and Decoding IncrementalEncoder Objects IncrementalDecoder Objects Stream Encoding and Decoding StreamWriter Objects StreamReader Objects StreamReaderWriter Objects StreamRecoder Objects Encodings and Unicode Standard Encodings Python Specific Encodings Text Encodings Binary Transforms Standalone Codec Functions Text Transforms encodings — Encodings package encodings.idna — Internationalized Domain Names in Applications encodings.mbcs — Windows ANSI codepage encodings.utf_8_sig — UTF-8 codec with BOM signature Data Types datetime — Basic date and time types Aware and naive objects Constants Available types Common properties Determining if an object is aware or naive timedelta objects Examples of usage: timedelta date objects Examples of usage: date datetime objects Examples of usage: datetime time objects Examples of usage: time tzinfo objects timezone objects strftime() and strptime() behavior strftime() and strptime() format codes Technical detail zoneinfo — IANA time zone support Using ZoneInfo Data sources Configuring the data sources Compile-time configuration Environment configuration Runtime configuration The ZoneInfo class String representations Pickle serialization Functions Globals Exceptions and warnings calendar — General calendar-related functions Command-line usage collections — Container datatypes ChainMap objects ChainMap Examples and Recipes Counter objects deque objects deque Recipes defaultdict objects defaultdict Examples namedtuple() Factory Function for Tuples with Named Fields OrderedDict objects OrderedDict Examples and Recipes UserDict objects UserList objects UserString objects collections.abc — Abstract Base Classes for Containers Collections Abstract Base Classes Collections Abstract Base Classes – Detailed Descriptions Examples and Recipes heapq — Heap queue algorithm Basic Examples Other Applications Priority Queue Implementation Notes Theory bisect — Array bisection algorithm Performance Notes Searching Sorted Lists Examples array — Efficient arrays of numeric values weakref — Weak references Weak Reference Objects Example Finalizer Objects Comparing finalizers with __del__() methods types — Dynamic type creation and names for built-in types Dynamic Type Creation Standard Interpreter Types Additional Utility Classes and Functions Coroutine Utility Functions copy — Shallow and deep copy operations pprint — Data pretty printer Functions PrettyPrinter Objects Example reprlib — Alternate repr() implementation Repr Objects Subclassing Repr Objects enum — Support for enumerations Module Contents Data Types Supported __dunder__ names Supported _sunder_ names Utilities and Decorators Notes graphlib — Functionality to operate with graph-like structures Exceptions Numeric and Mathematical Modules numbers — Numeric abstract base classes The numeric tower Notes for type implementers Adding More Numeric ABCs Implementing the arithmetic operations math — Mathematical functions Number-theoretic functions Floating point arithmetic Floating point manipulation functions Power, exponential and logarithmic functions Summation and product functions Angular conversion Trigonometric functions Hyperbolic functions Special functions Constants cmath — Mathematical functions for complex numbers Conversions to and from polar coordinates Power and logarithmic functions Trigonometric functions Hyperbolic functions Classification functions Constants decimal — Decimal fixed-point and floating-point arithmetic Quick-start tutorial Decimal objects Logical operands Context objects Constants Rounding modes Signals Floating-point notes Mitigating round-off error with increased precision Special values Working with threads Recipes Decimal FAQ fractions — Rational numbers random — Generate pseudo-random numbers Bookkeeping functions Functions for bytes Functions for integers Functions for sequences Discrete distributions Real-valued distributions Alternative Generator Notes on Reproducibility Examples Recipes Command-line usage Command-line example statistics — Mathematical statistics functions Averages and measures of central location Measures of spread Statistics for relations between two inputs Function details Exceptions NormalDist objects Examples and Recipes Classic probability problems Monte Carlo inputs for simulations Approximating binomial distributions Naive bayesian classifier Functional Programming Modules itertools — Functions creating iterators for efficient looping Itertool Functions Itertools Recipes functools — Higher-order functions and operations on callable objects partial Objects operator — Standard operators as functions Mapping Operators to Functions In-place Operators File and Directory Access pathlib — Object-oriented filesystem paths Basic use Exceptions Pure paths General properties Operators Accessing individual parts Methods and properties Concrete paths Parsing and generating URIs Expanding and resolving paths Querying file type and status Reading and writing files Reading directories Creating files and directories Copying, moving and deleting Permissions and ownership Pattern language Comparison to the glob module Comparison to the os and os.path modules Corresponding tools Protocols os.path — Common pathname manipulations stat — Interpreting stat() results filecmp — File and Directory Comparisons The dircmp class tempfile — Generate temporary files and directories Examples Deprecated functions and variables glob — Unix style pathname pattern expansion Examples fnmatch — Unix filename pattern matching linecache — Random access to text lines shutil — High-level file operations Directory and files operations Platform-dependent efficient copy operations copytree example rmtree example Archiving operations Archiving example Archiving example with base_dir Querying the size of the output terminal Data Persistence pickle — Python object serialization Relationship to other Python modules Comparison with marshal Comparison with json Data stream format Module Interface What can be pickled and unpickled? Pickling Class Instances Persistence of External Objects Dispatch Tables Handling Stateful Objects Custom Reduction for Types, Functions, and Other Objects Out-of-band Buffers Provider API Consumer API Example Restricting Globals Performance Examples Command-line interface copyreg — Register pickle support functions Example shelve — Python object persistence Restrictions Example marshal — Internal Python object serialization dbm — Interfaces to Unix “databases” dbm.sqlite3 — SQLite backend for dbm dbm.gnu — GNU database manager dbm.ndbm — New Database Manager dbm.dumb — Portable DBM implementation sqlite3 — DB-API 2.0 interface for SQLite databases Tutorial Reference Module functions Module constants Connection objects Cursor objects Row objects Blob objects PrepareProtocol objects Exceptions SQLite and Python types Default adapters and converters (deprecated) Command-line interface How-to guides How to use placeholders to bind values in SQL queries How to adapt custom Python types to SQLite values How to write adaptable objects How to register adapter callables How to convert SQLite values to custom Python types Adapter and converter recipes How to use connection shortcut methods How to use the connection context manager How to work with SQLite URIs How to create and use row factories How to handle non-UTF-8 text encodings Explanation Transaction control Transaction control via the autocommit attribute Transaction control via the isolation_level attribute Data Compression and Archiving The compression package compression.zstd — Compression compatible with the Zstandard format Exceptions Reading and writing compressed files Compressing and decompressing data in memory Zstandard dictionaries Advanced parameter control Miscellaneous Examples zlib — Compression compatible with gzip gzip — Support for gzip files Examples of usage Command-line interface Command-line options bz2 — Support for bzip2 compression (De)compression of files Incremental (de)compression One-shot (de)compression Examples of usage lzma — Compression using the LZMA algorithm Reading and writing compressed files Compressing and decompressing data in memory Miscellaneous Specifying custom filter chains Examples zipfile — Work with ZIP archives ZipFile objects Path objects PyZipFile objects ZipInfo objects Command-line interface Command-line options Decompression pitfalls From file itself File system limitations Resources limitations Interruption Default behaviors of extraction tarfile — Read and write tar archive files TarFile Objects TarInfo Objects Extraction filters Default named filters Filter errors Hints for further verification Supporting older Python versions Stateful extraction filter example Command-Line Interface Command-line options Examples Reading examples Writing examples Supported tar formats Unicode issues File Formats csv — CSV File Reading and Writing Module Contents Dialects and Formatting Parameters Reader Objects Writer Objects Examples configparser — Configuration file parser Quick Start Supported Datatypes Fallback Values Supported INI File Structure Unnamed Sections Interpolation of values Mapping Protocol Access Customizing Parser Behaviour Legacy API Examples ConfigParser Objects RawConfigParser Objects Exceptions tomllib — Parse TOML files Examples Conversion Table netrc — netrc file processing netrc Objects plistlib — Generate and parse Apple .plist files Examples Cryptographic Services hashlib — Secure hashes and message digests Hash algorithms Usage Constructors Attributes Hash Objects SHAKE variable length digests File hashing Key derivation BLAKE2 Creating hash objects Constants Examples Simple hashing Using different digest sizes Keyed hashing Randomized hashing Personalization Tree mode Credits hmac — Keyed-Hashing for Message Authentication secrets — Generate secure random numbers for managing secrets Random numbers Generating tokens How many bytes should tokens use? Other functions Recipes and best practices Generic Operating System Services os — Miscellaneous operating system interfaces File Names, Command Line Arguments, and Environment Variables Python UTF-8 Mode Process Parameters File Object Creation File Descriptor Operations Querying the size of a terminal Inheritance of File Descriptors Files and Directories Timer File Descriptors Linux extended attributes Process Management Interface to the scheduler Miscellaneous System Information Random numbers io — Core tools for working with streams Overview Text I/O Binary I/O Raw I/O Text Encoding Opt-in EncodingWarning High-level Module Interface Class hierarchy I/O Base Classes Raw File I/O Buffered Streams Text I/O Static Typing Performance Binary I/O Text I/O Multi-threading Reentrancy time — Time access and conversions Functions Clock ID Constants Timezone Constants logging — Logging facility for Python Logger Objects Logging Levels Handler Objects Formatter Objects Filter Objects LogRecord Objects LogRecord attributes LoggerAdapter Objects Thread Safety Module-Level Functions Module-Level Attributes Integration with the warnings module logging.config — Logging configuration Configuration functions Security considerations Configuration dictionary schema Dictionary Schema Details Incremental Configuration Object connections User-defined objects Handler configuration order Access to external objects Access to internal objects Import resolution and custom importers Configuring QueueHandler and QueueListener Configuration file format logging.handlers — Logging handlers StreamHandler FileHandler NullHandler WatchedFileHandler BaseRotatingHandler RotatingFileHandler TimedRotatingFileHandler SocketHandler DatagramHandler SysLogHandler NTEventLogHandler SMTPHandler MemoryHandler HTTPHandler QueueHandler QueueListener platform — Access to underlying platform’s identifying data Cross platform Java platform Windows platform macOS platform iOS platform Unix platforms Linux platforms Android platform Command-line usage errno — Standard errno system symbols ctypes — A foreign function library for Python ctypes tutorial Loading dynamic link libraries Accessing functions from loaded dlls Calling functions Fundamental data types Calling functions, continued Calling variadic functions Calling functions with your own custom data types Specifying the required argument types (function prototypes) Return types Passing pointers (or: passing parameters by reference) Structures and unions Structure/union layout, alignment and byte order Bit fields in structures and unions Arrays Pointers Thread safety without the GIL Type conversions Incomplete Types Callback functions Accessing values exported from dlls Surprises Variable-sized data types ctypes reference Finding shared libraries Listing loaded shared libraries Loading shared libraries Foreign functions Function prototypes Utility functions Data types Fundamental data types Structured data types Arrays and pointers Exceptions Command-line interface libraries argparse — Parser for command-line options, arguments and subcommands ArgumentParser objects prog usage description epilog parents formatter_class prefix_chars fromfile_prefix_chars argument_default allow_abbrev conflict_handler add_help exit_on_error suggest_on_error color The add_argument() method name or flags action nargs const default type choices required help metavar dest deprecated Action classes The parse_args() method Option value syntax Invalid arguments Arguments containing - Argument abbreviations (prefix matching) Beyond sys.argv The Namespace object Other utilities Subcommands FileType objects Argument groups Mutual exclusion Parser defaults Printing help Partial parsing Customizing file parsing Exiting methods Intermixed parsing Registering custom types or actions Exceptions Argparse Tutorial Concepts The basics Introducing Positional arguments Introducing Optional arguments Short options Combining Positional and Optional arguments Getting a little more advanced Specifying ambiguous arguments Conflicting options How to translate the argparse output Custom type converters Conclusion Migrating optparse code to argparse optparse — Parser for command line options Choosing an argument parsing library Introduction Background Terminology What are options for? What are positional arguments for? Tutorial Understanding option actions The store action Handling boolean (flag) options Other actions Default values Generating help Grouping Options Printing a version string How optparse handles errors Putting it all together Reference Guide Creating the parser Populating the parser Defining options Option attributes Standard option actions Standard option types Parsing arguments Querying and manipulating your option parser Conflicts between options Cleanup Other methods Option Callbacks Defining a callback option How callbacks are called Raising errors in a callback Callback example 1: trivial callback Callback example 2: check option order Callback example 3: check option order (generalized) Callback example 4: check arbitrary condition Callback example 5: fixed arguments Callback example 6: variable arguments Extending optparse Adding new types Adding new actions Exceptions getpass — Portable password input fileinput — Iterate over lines from multiple input streams curses — Terminal handling for character-cell displays Functions Window Objects Constants curses.textpad — Text input widget for curses programs Textbox objects curses.ascii — Utilities for ASCII characters curses.panel — A panel stack extension for curses Functions Panel Objects cmd — Support for line-oriented command interpreters Cmd Objects Cmd Example Concurrent Execution threading — Thread-based parallelism Introduction GIL and performance considerations Reference Thread-local data Thread objects Lock objects RLock objects Condition objects Semaphore objects Semaphore example Event objects Timer objects Barrier objects Using locks, conditions, and semaphores in the with statement multiprocessing — Process-based parallelism Introduction The Process class Contexts and start methods Exchanging objects between processes Synchronization between processes Sharing state between processes Using a pool of workers Reference Global start method Process and exceptions Pipes and Queues Miscellaneous Connection Objects Synchronization primitives Shared ctypes Objects The multiprocessing.sharedctypes module Managers Customized managers Using a remote manager Proxy Objects Cleanup Process Pools Listeners and Clients Address Formats Authentication keys Logging The multiprocessing.dummy module Programming guidelines All start methods The spawn and forkserver start methods Examples multiprocessing.shared_memory — Shared memory for direct access across processes The concurrent package concurrent.futures — Launching parallel tasks Executor Objects ThreadPoolExecutor ThreadPoolExecutor Example InterpreterPoolExecutor ProcessPoolExecutor ProcessPoolExecutor Example Future Objects Module Functions Exception classes concurrent.interpreters — Multiple interpreters in the same process Key details Introduction Multiple Interpreters and Isolation Running in an Interpreter Concurrency and Parallelism Communication Between Interpreters “Sharing” Objects Reference Interpreter objects Exceptions Communicating Between Interpreters Basic usage subprocess — Subprocess management Using the subprocess Module Frequently Used Arguments Popen Constructor Exceptions Security Considerations Popen Objects Windows Popen Helpers Windows Constants Older high-level API Replacing Older Functions with the subprocess Module Replacing /bin/sh shell command substitution Replacing shell pipeline Replacing os.system() Replacing the os.spawn family Replacing os.popen() Legacy Shell Invocation Functions Notes Timeout Behavior Converting an argument sequence to a string on Windows Disable use of posix_spawn() sched — Event scheduler Scheduler Objects queue — A synchronized queue class Queue Objects Waiting for task completion Terminating queues SimpleQueue Objects contextvars — Context Variables Context Variables Manual Context Management asyncio support _thread — Low-level threading API Networking and Interprocess Communication asyncio — Asynchronous I/O Runners Running an asyncio Program Runner context manager Handling Keyboard Interruption Coroutines and Tasks Coroutines Awaitables Creating Tasks Task Cancellation Task Groups Terminating a Task Group Sleeping Running Tasks Concurrently Eager Task Factory Shielding From Cancellation Timeouts Waiting Primitives Running in Threads Scheduling From Other Threads Introspection Task Object Streams StreamReader StreamWriter Examples TCP echo client using streams TCP echo server using streams Get HTTP headers Register an open socket to wait for data using streams Synchronization Primitives Lock Event Condition Semaphore BoundedSemaphore Barrier Subprocesses Creating Subprocesses Constants Interacting with Subprocesses Subprocess and Threads Examples Queues Queue Priority Queue LIFO Queue Exceptions Examples Exceptions Call Graph Introspection Low level utility functions Event Loop Event Loop Methods Running and stopping the loop Scheduling callbacks Scheduling delayed callbacks Creating Futures and Tasks Opening network connections Creating network servers Transferring files TLS Upgrade Watching file descriptors Working with socket objects directly DNS Working with pipes Unix signals Executing code in thread or process pools Error Handling API Enabling debug mode Running Subprocesses Callback Handles Server Objects Event Loop Implementations Examples Hello World with call_soon() Display the current date with call_later() Watch a file descriptor for read events Set signal handlers for SIGINT and SIGTERM Futures Future Functions Future Object Transports and Protocols Transports Transports Hierarchy Base Transport Read-only Transports Write-only Transports Datagram Transports Subprocess Transports Protocols Base Protocols Base Protocol Streaming Protocols Buffered Streaming Protocols Datagram Protocols Subprocess Protocols Examples TCP Echo Server TCP Echo Client UDP Echo Server UDP Echo Client Connecting Existing Sockets loop.subprocess_exec() and SubprocessProtocol Policies Getting and Setting the Policy Policy Objects Custom Policies Platform Support All Platforms Windows Subprocess Support on Windows macOS Extending Writing a Custom Event Loop Future and Task private constructors Task lifetime support High-level API Index Tasks Queues Subprocesses Streams Synchronization Exceptions Low-level API Index Obtaining the Event Loop Event Loop Methods Transports Protocols Event Loop Policies Developing with asyncio Debug Mode Concurrency and Multithreading Running Blocking Code Logging Detect never-awaited coroutines Detect never-retrieved exceptions socket — Low-level networking interface Socket families Module contents Exceptions Constants Functions Creating sockets Other functions Socket Objects Notes on socket timeouts Timeouts and the connect method Timeouts and the accept method Example ssl — TLS/SSL wrapper for socket objects Functions, Constants, and Exceptions Socket creation Context creation Exceptions Random generation Certificate handling Constants SSL Sockets SSL Contexts Certificates Certificate chains CA certificates Combined key and certificate Self-signed certificates Examples Testing for SSL support Client-side operation Server-side operation Notes on non-blocking sockets Memory BIO Support SSL session Security considerations Best defaults Manual settings Verifying certificates Protocol versions Cipher selection Multi-processing TLS 1.3 select — Waiting for I/O completion /dev/poll Polling Objects Edge and Level Trigger Polling (epoll) Objects Polling Objects Kqueue Objects Kevent Objects selectors — High-level I/O multiplexing Introduction Classes Examples signal — Set handlers for asynchronous events General rules Execution of Python signal handlers Signals and threads Module contents Examples Note on SIGPIPE Note on Signal Handlers and Exceptions mmap — Memory-mapped file support MADV_* Constants MAP_* Constants Internet Data Handling email — An email and MIME handling package email.message: Representing an email message email.parser: Parsing email messages FeedParser API Parser API Additional notes email.generator: Generating MIME documents email.policy: Policy Objects email.errors: Exception and Defect classes email.headerregistry: Custom Header Objects email.contentmanager: Managing MIME Content Content Manager Instances email: Examples email.message.Message: Representing an email message using the compat32 API email.mime: Creating email and MIME objects from scratch email.header: Internationalized headers email.charset: Representing character sets email.encoders: Encoders email.utils: Miscellaneous utilities email.iterators: Iterators json — JSON encoder and decoder Basic Usage Encoders and Decoders Exceptions Standard Compliance and Interoperability Character Encodings Infinite and NaN Number Values Repeated Names Within an Object Top-level Non-Object, Non-Array Values Implementation Limitations Command-line interface Command-line options mailbox — Manipulate mailboxes in various formats Mailbox objects Maildir objects mbox objects MH objects Babyl objects MMDF objects Message objects MaildirMessage objects mboxMessage objects MHMessage objects BabylMessage objects MMDFMessage objects Exceptions Examples mimetypes — Map filenames to MIME types MimeTypes objects Command-line usage Command-line example base64 — Base16, Base32, Base64, Base85 Data Encodings RFC 4648 Encodings Base85 Encodings Legacy Interface Security Considerations binascii — Convert between binary and ASCII quopri — Encode and decode MIME quoted-printable data Structured Markup Processing Tools html — HyperText Markup Language support html.parser — Simple HTML and XHTML parser Example HTML Parser Application HTMLParser Methods Examples html.entities — Definitions of HTML general entities XML Processing Modules XML security xml.etree.ElementTree — The ElementTree XML API Tutorial XML tree and elements Parsing XML Pull API for non-blocking parsing Finding interesting elements Modifying an XML File Building XML documents Parsing XML with Namespaces XPath support Example Supported XPath syntax Reference Functions XInclude support Example Reference Functions Element Objects ElementTree Objects QName Objects TreeBuilder Objects XMLParser Objects XMLPullParser Objects Exceptions xml.dom — The Document Object Model API Module Contents Objects in the DOM DOMImplementation Objects Node Objects NodeList Objects DocumentType Objects Document Objects Element Objects Attr Objects NamedNodeMap Objects Comment Objects Text and CDATASection Objects ProcessingInstruction Objects Exceptions Conformance Type Mapping Accessor Methods xml.dom.minidom — Minimal DOM implementation DOM Objects DOM Example minidom and the DOM standard xml.dom.pulldom — Support for building partial DOM trees DOMEventStream Objects xml.sax — Support for SAX2 parsers SAXException Objects xml.sax.handler — Base classes for SAX handlers ContentHandler Objects DTDHandler Objects EntityResolver Objects ErrorHandler Objects LexicalHandler Objects xml.sax.saxutils — SAX Utilities xml.sax.xmlreader — Interface for XML parsers XMLReader Objects IncrementalParser Objects Locator Objects InputSource Objects The Attributes Interface The AttributesNS Interface xml.parsers.expat — Fast XML parsing using Expat XMLParser Objects ExpatError Exceptions Example Content Model Descriptions Expat error constants Internet Protocols and Support webbrowser — Convenient web-browser controller Command-line interface Browser controller objects wsgiref — WSGI Utilities and Reference Implementation wsgiref.util – WSGI environment utilities wsgiref.headers – WSGI response header tools wsgiref.simple_server – a simple WSGI HTTP server wsgiref.validate — WSGI conformance checker wsgiref.handlers – server/gateway base classes wsgiref.types – WSGI types for static type checking Examples urllib — URL handling modules urllib.request — Extensible library for opening URLs Request Objects OpenerDirector Objects BaseHandler Objects HTTPRedirectHandler Objects HTTPCookieProcessor Objects ProxyHandler Objects HTTPPasswordMgr Objects HTTPPasswordMgrWithPriorAuth Objects AbstractBasicAuthHandler Objects HTTPBasicAuthHandler Objects ProxyBasicAuthHandler Objects AbstractDigestAuthHandler Objects HTTPDigestAuthHandler Objects ProxyDigestAuthHandler Objects HTTPHandler Objects HTTPSHandler Objects FileHandler Objects DataHandler Objects FTPHandler Objects CacheFTPHandler Objects UnknownHandler Objects HTTPErrorProcessor Objects Examples Legacy interface urllib.request Restrictions urllib.response — Response classes used by urllib urllib.parse — Parse URLs into components URL Parsing URL parsing security Parsing ASCII Encoded Bytes Structured Parse Results URL Quoting urllib.error — Exception classes raised by urllib.request urllib.robotparser — Parser for robots.txt http — HTTP modules HTTP status codes HTTP status category HTTP methods http.client — HTTP protocol client HTTPConnection Objects HTTPResponse Objects Examples HTTPMessage Objects ftplib — FTP protocol client Reference FTP objects FTP_TLS objects Module variables poplib — POP3 protocol client POP3 Objects POP3 Example imaplib — IMAP4 protocol client IMAP4 Objects IMAP4 Example smtplib — SMTP protocol client SMTP Objects SMTP Example uuid — UUID objects according to RFC 9562 Command-Line Usage Example Command-Line Example socketserver — A framework for network servers Server Creation Notes Server Objects Request Handler Objects Examples socketserver.TCPServer Example socketserver.UDPServer Example Asynchronous Mixins http.server — HTTP servers Command-line interface Security considerations http.cookies — HTTP state management Cookie Objects Morsel Objects Example http.cookiejar — Cookie handling for HTTP clients CookieJar and FileCookieJar Objects FileCookieJar subclasses and co-operation with web browsers CookiePolicy Objects DefaultCookiePolicy Objects Cookie Objects Examples xmlrpc — XMLRPC server and client modules xmlrpc.client — XML-RPC client access ServerProxy Objects DateTime Objects Binary Objects Fault Objects ProtocolError Objects MultiCall Objects Convenience Functions Example of Client Usage Example of Client and Server Usage xmlrpc.server — Basic XML-RPC servers SimpleXMLRPCServer Objects SimpleXMLRPCServer Example CGIXMLRPCRequestHandler Documenting XMLRPC server DocXMLRPCServer Objects DocCGIXMLRPCRequestHandler ipaddress — IPv4/IPv6 manipulation library Convenience factory functions IP Addresses Address objects Conversion to Strings and Integers Operators Comparison operators Arithmetic operators IP Network definitions Prefix, net mask and host mask Network objects Operators Logical operators Iteration Networks as containers of addresses Interface objects Operators Logical operators Other Module Level Functions Custom Exceptions Multimedia Services wave — Read and write WAV files Wave_read Objects Wave_write Objects colorsys — Conversions between color systems Internationalization gettext — Multilingual internationalization services GNU gettext API Class-based API The NullTranslations class The GNUTranslations class Solaris message catalog support The Catalog constructor Internationalizing your programs and modules Localizing your module Localizing your application Changing languages on the fly Deferred translations Acknowledgements locale — Internationalization services Background, details, hints, tips and caveats Locale names For extension writers and programs that embed Python Access to message catalogs Graphical user interfaces with Tk tkinter — Python interface to Tcl/Tk Architecture Tkinter Modules Tkinter Life Preserver A Hello World Program Important Tk Concepts Understanding How Tkinter Wraps Tcl/Tk How do I…? What option does…? Navigating the Tcl/Tk Reference Manual Threading model Handy Reference Setting Options The Packer Packer Options Coupling Widget Variables The Window Manager Tk Option Data Types Bindings and Events The index Parameter Images File Handlers tkinter.colorchooser — Color choosing dialog tkinter.font — Tkinter font wrapper Tkinter Dialogs tkinter.simpledialog — Standard Tkinter input dialogs tkinter.filedialog — File selection dialogs Native Load/Save Dialogs tkinter.commondialog — Dialog window templates tkinter.messagebox — Tkinter message prompts tkinter.scrolledtext — Scrolled Text Widget tkinter.dnd — Drag and drop support tkinter.ttk — Tk themed widgets Using Ttk Ttk Widgets Widget Standard Options Scrollable Widget Options Label Options Compatibility Options Widget States ttk.Widget Combobox Options Virtual events ttk.Combobox Spinbox Options Virtual events ttk.Spinbox Notebook Options Tab Options Tab Identifiers Virtual Events ttk.Notebook Progressbar Options ttk.Progressbar Separator Options Sizegrip Platform-specific notes Bugs Treeview Options Item Options Tag Options Column Identifiers Virtual Events ttk.Treeview Ttk Styling Layouts IDLE — Python editor and shell Menus File menu (Shell and Editor) Edit menu (Shell and Editor) Format menu (Editor window only) Run menu (Editor window only) Shell menu (Shell window only) Debug menu (Shell window only) Options menu (Shell and Editor) Window menu (Shell and Editor) Help menu (Shell and Editor) Context menus Editing and Navigation Editor windows Key bindings Automatic indentation Search and Replace Completions Calltips Format block Code Context Shell window Text colors Startup and Code Execution Command-line usage Startup failure Running user code User output in Shell Developing tkinter applications Running without a subprocess Help and Preferences Help sources Setting preferences IDLE on macOS Extensions idlelib — implementation of IDLE application turtle — Turtle graphics Introduction Get started Tutorial Starting a turtle environment Basic drawing Pen control The turtle’s position Making algorithmic patterns How to… Get started as quickly as possible Automatically begin and end filling Use the turtle module namespace Use turtle graphics in a script Use object-oriented turtle graphics Turtle graphics reference Turtle methods Methods of TurtleScreen/Screen Methods of RawTurtle/Turtle and corresponding functions Turtle motion Tell Turtle’s state Settings for measurement Pen control Drawing state Color control Filling More drawing control Turtle state Visibility Appearance Using events Special Turtle methods Compound shapes Methods of TurtleScreen/Screen and corresponding functions Window control Animation control Using screen events Input methods Settings and special methods Methods specific to Screen, not inherited from TurtleScreen Public classes Explanation Help and configuration How to use help Translation of docstrings into different languages How to configure Screen and Turtles turtledemo — Demo scripts Changes since Python 2.6 Changes since Python 3.0 Development Tools typing — Support for type hints Specification for the Python Type System Type aliases NewType Annotating callable objects Generics Annotating tuples The type of class objects Annotating generators and coroutines User-defined generic types The Any type Nominal vs structural subtyping Module contents Special typing primitives Special types Special forms Building generic types and type aliases Other special directives Protocols ABCs and Protocols for working with I/O Functions and decorators Introspection helpers Constant Deprecated aliases Aliases to built-in types Aliases to types in collections Aliases to other concrete types Aliases to container ABCs in collections.abc Aliases to asynchronous ABCs in collections.abc Aliases to other ABCs in collections.abc Aliases to contextlib ABCs Deprecation Timeline of Major Features pydoc — Documentation generator and online help system Python Development Mode Effects of the Python Development Mode ResourceWarning Example Bad file descriptor error example doctest — Test interactive Python examples Simple Usage: Checking Examples in Docstrings Simple Usage: Checking Examples in a Text File Command-line Usage How It Works Which Docstrings Are Examined? How are Docstring Examples Recognized? What’s the Execution Context? What About Exceptions? Option Flags Directives Warnings Basic API Unittest API Advanced API DocTest Objects Example Objects DocTestFinder objects DocTestParser objects TestResults objects DocTestRunner objects OutputChecker objects Debugging Soapbox unittest — Unit testing framework Basic example Command-Line Interface Command-line options Test Discovery Organizing test code Re-using old test code Skipping tests and expected failures Distinguishing test iterations using subtests Classes and functions Test cases Grouping tests Loading and running tests load_tests Protocol Class and Module Fixtures setUpClass and tearDownClass setUpModule and tearDownModule Signal Handling unittest.mock — mock object library Quick Guide The Mock Class Calling Deleting Attributes Mock names and the name attribute Attaching Mocks as Attributes The patchers patch patch.object patch.dict patch.multiple patch methods: start and stop patch builtins TEST_PREFIX Nesting Patch Decorators Where to patch Patching Descriptors and Proxy Objects MagicMock and magic method support Mocking Magic Methods Magic Mock Helpers sentinel DEFAULT call create_autospec ANY FILTER_DIR mock_open Autospeccing Sealing mocks Order of precedence of side_effect, return_value and wraps unittest.mock — getting started Using Mock Mock Patching Methods Mock for Method Calls on an Object Mocking Classes Naming your mocks Tracking all Calls Setting Return Values and Attributes Raising exceptions with mocks Side effect functions and iterables Mocking asynchronous iterators Mocking asynchronous context manager Creating a Mock from an Existing Object Using side_effect to return per file content Patch Decorators Further Examples Mocking chained calls Partial mocking Mocking a Generator Method Applying the same patch to every test method Mocking Unbound Methods Checking multiple calls with mock Coping with mutable arguments Nesting Patches Mocking a dictionary with MagicMock Mock subclasses and their attributes Mocking imports with patch.dict Tracking order of calls and less verbose call assertions More complex argument matching test — Regression tests package for Python Writing Unit Tests for the test package Running tests using the command-line interface test.support — Utilities for the Python test suite test.support.socket_helper — Utilities for socket tests test.support.script_helper — Utilities for the Python execution tests test.support.bytecode_helper — Support tools for testing correct bytecode generation test.support.threading_helper — Utilities for threading tests test.support.os_helper — Utilities for os tests test.support.import_helper — Utilities for import tests test.support.warnings_helper — Utilities for warnings tests Debugging and Profiling Audit events table bdb — Debugger framework faulthandler — Dump the Python traceback Dumping the traceback Dumping the C stack C Stack Compatibility Fault handler state Dumping the tracebacks after a timeout Dumping the traceback on a user signal Issue with file descriptors Example pdb — The Python Debugger Command-line interface Debugger commands The Python Profilers Introduction to the profilers Instant User’s Manual profile and cProfile Module Reference The Stats Class What Is Deterministic Profiling? Limitations Calibration Using a custom timer timeit — Measure execution time of small code snippets Basic Examples Python Interface Command-Line Interface Examples trace — Trace or track Python statement execution Command-Line Usage Main options Modifiers Filters Programmatic Interface tracemalloc — Trace memory allocations Examples Display the top 10 Compute differences Get the traceback of a memory block Pretty top Record the current and peak size of all traced memory blocks API Functions DomainFilter Filter Frame Snapshot Statistic StatisticDiff Trace Traceback Software Packaging and Distribution ensurepip — Bootstrapping the pip installer Command-line interface Module API venv — Creation of virtual environments Creating virtual environments How venvs work API An example of extending EnvBuilder zipapp — Manage executable Python zip archives Basic Example Command-Line Interface Python API Examples Specifying the Interpreter Creating Standalone Applications with zipapp Caveats The Python Zip Application Archive Format Python Runtime Services sys — System-specific parameters and functions sys.monitoring — Execution event monitoring Tool identifiers Registering and using tools Events Local events Deprecated event Ancillary events Other events The STOP_ITERATION event Turning events on and off Setting events globally Per code object events Disabling events Registering callback functions Callback function arguments sysconfig — Provide access to Python’s configuration information Configuration variables Installation paths User scheme posix_user nt_user osx_framework_user Home scheme posix_home Prefix scheme posix_prefix nt Installation path functions Other functions Command-line usage builtins — Built-in objects __main__ — Top-level code environment __name__ == '__main__' What is the “top-level code environment”? Idiomatic Usage Packaging Considerations __main__.py in Python Packages Idiomatic Usage import __main__ warnings — Warning control Warning Categories The Warnings Filter Repeated Warning Suppression Criteria Describing Warning Filters Default Warning Filter Overriding the default filter Temporarily Suppressing Warnings Testing Warnings Updating Code For New Versions of Dependencies Available Functions Available Context Managers Concurrent safety of Context Managers dataclasses — Data Classes Module contents Post-init processing Class variables Init-only variables Frozen instances Inheritance Re-ordering of keyword-only parameters in __init__() Default factory functions Mutable default values Descriptor-typed fields contextlib — Utilities for with-statement contexts Utilities Examples and Recipes Supporting a variable number of context managers Catching exceptions from __enter__ methods Cleaning up in an __enter__ implementation Replacing any use of try-finally and flag variables Using a context manager as a function decorator Single use, reusable and reentrant context managers Reentrant context managers Reusable context managers abc — Abstract Base Classes atexit — Exit handlers atexit Example traceback — Print or retrieve a stack traceback Module-Level Functions TracebackException Objects StackSummary Objects FrameSummary Objects Examples of Using the Module-Level Functions Examples of Using TracebackException __future__ — Future statement definitions Module Contents gc — Garbage Collector interface inspect — Inspect live objects Types and members Retrieving source code Introspecting callables with the Signature object Classes and functions The interpreter stack Fetching attributes statically Current State of Generators, Coroutines, and Asynchronous Generators Code Objects Bit Flags Buffer flags Command-line interface annotationlib — Functionality for introspecting annotations Annotation semantics Classes Functions Recipes Using annotations in a metaclass Limitations of the STRING format Limitations of the FORWARDREF format Security implications of introspecting annotations site — Site-specific configuration hook sitecustomize usercustomize Readline configuration Module contents Command-line interface Custom Python Interpreters code — Interpreter base classes Interactive Interpreter Objects Interactive Console Objects codeop — Compile Python code Importing Modules zipimport — Import modules from Zip archives zipimporter Objects Examples pkgutil — Package extension utility modulefinder — Find modules used by a script Example usage of ModuleFinder runpy — Locating and executing Python modules importlib — The implementation of import Introduction Functions importlib.abc – Abstract base classes related to import importlib.machinery – Importers and path hooks importlib.util – Utility code for importers Examples Importing programmatically Checking if a module can be imported Importing a source file directly Implementing lazy imports Setting up an importer Approximating importlib.import_module() importlib.resources – Package resource reading, opening and access Functional API importlib.resources.abc – Abstract base classes for resources importlib.metadata – Accessing package metadata Overview Functional API Entry points Distribution metadata Distribution versions Distribution files Distribution requirements Mapping import to distribution packages Distributions Distribution Discovery Implementing Custom Providers Example The initialization of the sys.path module search path Virtual Environments _pth files Embedded Python Python Language Services ast — Abstract syntax trees Abstract grammar Node classes Root nodes Literals Variables Expressions Subscripting Comprehensions Statements Imports Control flow Pattern matching Type annotations Type parameters Function and class definitions Async and await ast helpers Compiler flags Command-line usage symtable — Access to the compiler’s symbol tables Generating Symbol Tables Examining Symbol Tables Command-Line Usage token — Constants used with Python parse trees keyword — Testing for Python keywords tokenize — Tokenizer for Python source Tokenizing Input Command-Line Usage Examples tabnanny — Detection of ambiguous indentation pyclbr — Python module browser support Function Objects Class Objects py_compile — Compile Python source files Command-Line Interface compileall — Byte-compile Python libraries Command-line use Public functions dis — Disassembler for Python bytecode Command-line interface Bytecode analysis Analysis functions Python Bytecode Instructions Opcode collections pickletools — Tools for pickle developers Command-line usage Command-line options Programmatic interface MS Windows Specific Services msvcrt — Useful routines from the MS VC++ runtime File Operations Console I/O Other Functions winreg — Windows registry access Functions Constants HKEY_* Constants Access Rights 64-bit Specific Value Types Registry Handle Objects winsound — Sound-playing interface for Windows Unix-specific services shlex — Simple lexical analysis shlex Objects Parsing Rules Improved Compatibility with Shells posix — The most common POSIX system calls Large File Support Notable Module Contents pwd — The password database grp — The group database termios — POSIX style tty control Example tty — Terminal control functions pty — Pseudo-terminal utilities Example fcntl — The fcntl and ioctl system calls resource — Resource usage information Resource Limits Resource Usage syslog — Unix syslog library routines Examples Simple example Modules command-line interface (CLI) Superseded Modules getopt — C-style parser for command line options Removed Modules Security Considerations Extending and Embedding the Python Interpreter Recommended third party tools Creating extensions without third party tools 1. Extending Python with C or C++ 1.1. A Simple Example 1.2. Intermezzo: Errors and Exceptions 1.3. Back to the Example 1.4. The Module’s Method Table and Initialization Function 1.5. Compilation and Linkage 1.6. Calling Python Functions from C 1.7. Extracting Parameters in Extension Functions 1.8. Keyword Parameters for Extension Functions 1.9. Building Arbitrary Values 1.10. Reference Counts 1.10.1. Reference Counting in Python 1.10.2. Ownership Rules 1.10.3. Thin Ice 1.10.4. NULL Pointers 1.11. Writing Extensions in C++ 1.12. Providing a C API for an Extension Module 2. Defining Extension Types: Tutorial 2.1. The Basics 2.2. Adding data and methods to the Basic example 2.3. Providing finer control over data attributes 2.4. Supporting cyclic garbage collection 2.5. Subclassing other types 3. Defining Extension Types: Assorted Topics 3.1. Finalization and De-allocation 3.2. Object Presentation 3.3. Attribute Management 3.3.1. Generic Attribute Management 3.3.2. Type-specific Attribute Management 3.4. Object Comparison 3.5. Abstract Protocol Support 3.6. Weak Reference Support 3.7. More Suggestions 4. Building C and C++ Extensions 4.1. Building C and C++ Extensions with setuptools 5. Building C and C++ Extensions on Windows 5.1. A Cookbook Approach 5.2. Differences Between Unix and Windows 5.3. Using DLLs in Practice Embedding the CPython runtime in a larger application 1. Embedding Python in Another Application 1.1. Very High Level Embedding 1.2. Beyond Very High Level Embedding: An overview 1.3. Pure Embedding 1.4. Extending Embedded Python 1.5. Embedding Python in C++ 1.6. Compiling and Linking under Unix-like systems Python/C API reference manual Introduction Language version compatibility Coding standards Include Files Useful macros Docstring macros General utility macros Numeric utilities Assertion utilities Type size utilities Macro definition utilities Declaration utilities Outdated macros Objects, Types and Reference Counts Reference Counts Reference Count Details Types Exceptions Embedding Python Debugging Builds Recommended third party tools C API Stability Unstable C API Stable Application Binary Interface Limited C API Stable ABI Limited API Scope and Performance Limited API Caveats Platform Considerations Contents of Limited API The Very High Level Layer Available start symbols Stack Effects Reference Counting Exception Handling Printing and clearing Raising exceptions Issuing warnings Querying the error indicator Signal Handling Exception Classes Exception Objects Unicode Exception Objects Recursion Control Exception and warning types Exception types OSError aliases Warning types Tracebacks Defining extension modules Multiple module instances Initialization function Multi-phase initialization Legacy single-phase initialization Utilities Operating System Utilities System Functions Process Control Importing Modules Data marshalling support Parsing arguments and building values Parsing arguments Strings and buffers Numbers Other objects API Functions Building values String conversion and formatting Character classification and conversion PyHash API Reflection Codec registry and support functions Codec lookup API Registry API for Unicode encoding error handlers Codec utility variables PyTime C API Types Clock Functions Raw Clock Functions Conversion functions Support for Perf Maps Abstract Objects Layer Object Protocol Call Protocol The tp_call Protocol The Vectorcall Protocol Recursion Control Vectorcall Support API Object Calling API Call Support API Number Protocol Sequence Protocol Mapping Protocol Iterator Protocol Buffer Protocol Buffer structure Buffer request types request-independent fields readonly, format shape, strides, suboffsets contiguity requests compound requests Complex arrays NumPy-style: shape and strides PIL-style: shape, strides and suboffsets Buffer-related functions Concrete Objects Layer Fundamental Objects Type Objects Creating Heap-Allocated Types The None Object Numeric Objects Integer Objects Export API PyLongWriter API Deprecated API Boolean Objects Floating-Point Objects Pack and Unpack functions Pack functions Unpack functions Complex Number Objects Complex Numbers as C Structures Complex Numbers as Python Objects Sequence Objects Bytes Objects Byte Array Objects Type check macros Direct API functions Macros Unicode Objects and Codecs Unicode Objects Unicode Type Unicode Character Properties Creating and accessing Unicode strings Locale Encoding File System Encoding wchar_t Support Built-in Codecs Generic Codecs UTF-8 Codecs UTF-32 Codecs UTF-16 Codecs UTF-7 Codecs Unicode-Escape Codecs Raw-Unicode-Escape Codecs Latin-1 Codecs ASCII Codecs Character Map Codecs MBCS codecs for Windows Methods and Slot Functions PyUnicodeWriter Deprecated API Tuple Objects Struct Sequence Objects List Objects Container Objects Dictionary Objects Dictionary View Objects Ordered Dictionaries Set Objects Deprecated API Function Objects Function Objects Instance Method Objects Method Objects Cell Objects Code Objects Code Object Flags Extra information Other Objects File Objects Deprecated API Module Objects Module definitions Module slots Creating extension modules dynamically Support functions Module lookup (single-phase initialization) Iterator Objects Range Objects Builtin Iterator Types Other Iterator Objects Descriptor Objects Built-in descriptors Slice Objects Ellipsis Object MemoryView objects Pickle buffer objects Weak Reference Objects Capsules Frame Objects Frame Locals Proxies Legacy Local Variable APIs Internal Frames Generator Objects Asynchronous Generator Objects Deprecated API Coroutine Objects Context Variables Objects Objects for Type Hinting C API for extension modules Curses C API Internal data DateTime Objects Internal data Interpreter initialization and finalization Before Python initialization Global configuration variables Initializing and finalizing the interpreter Cautions regarding runtime finalization Process-wide parameters Thread states and the global interpreter lock Detaching the thread state from extension code APIs Non-Python created threads Supporting subinterpreters in non-Python threads Cautions about fork() High-level APIs GIL-state APIs Low-level APIs Asynchronous notifications Operating system thread APIs Synchronization primitives Python critical section API Legacy locking APIs Thread-local storage support Thread-specific storage API Dynamic allocation Methods Legacy APIs Multiple interpreters in a Python process A per-interpreter GIL Bugs and caveats High-level APIs Low-level APIs Advanced debugger support Profiling and tracing Reference tracing Python Initialization Configuration PyInitConfig C API Example Create Config Error Handling Get Options Set Options Module Initialize Python Configuration Options Runtime Python configuration API PyConfig C API Example PyWideStringList PyStatus PyPreConfig Preinitialize Python with PyPreConfig PyConfig Initialization with PyConfig Isolated Configuration Python Configuration Python Path Configuration Py_GetArgcArgv() Delaying main module execution Memory Management Overview Allocator Domains Raw Memory Interface Memory Interface Deprecated aliases Object allocators Default Memory Allocators Customize Memory Allocators Debug hooks on the Python memory allocators The pymalloc allocator Customize pymalloc Arena Allocator The mimalloc allocator tracemalloc C API Examples Object Implementation Support Allocating Objects on the Heap Deprecated aliases Object Life Cycle Life Events Cyclic Isolate Destruction Functions Common Object Structures Base object types and macros Implementing functions and methods Accessing attributes of extension types Member flags Member types Defining Getters and Setters Type Object Structures Quick Reference “tp slots” sub-slots slot typedefs PyTypeObject Definition PyObject Slots PyVarObject Slots PyTypeObject Slots Static Types Heap Types Number Object Structures Mapping Object Structures Sequence Object Structures Buffer Object Structures Async Object Structures Slot Type typedefs Examples Supporting Cyclic Garbage Collection Controlling the Garbage Collector State Querying Garbage Collector State API and ABI Versioning Build-time version constants Run-time version Bit-packing macros Monitoring C API Generating Execution Events Managing the Monitoring State Installing Python Modules Key terms Basic usage How do I …? … install pip in versions of Python prior to Python 3.4? … install packages just for the current user? … install scientific Python packages? … work with multiple versions of Python installed in parallel? Common installation issues Installing into the system Python on Linux Pip not installed Installing binary extensions Python HOWTOs Python Frequently Asked Questions General Python FAQ General Information Python in the real world Programming FAQ General Questions Core Language Numbers and strings Performance Sequences (Tuples/Lists) Objects Modules Design and History FAQ Why does Python use indentation for grouping of statements? Why am I getting strange results with simple arithmetic operations? Why are floating-point calculations so inaccurate? Why are Python strings immutable? Why must ‘self’ be used explicitly in method definitions and calls? Why can’t I use an assignment in an expression? Why does Python use methods for some functionality (e.g. list.index()) but functions for other (e.g. len(list))? Why is join() a string method instead of a list or tuple method? How fast are exceptions? Why isn’t there a switch or case statement in Python? Can’t you emulate threads in the interpreter instead of relying on an OS-specific thread implementation? Why can’t lambda expressions contain statements? Can Python be compiled to machine code, C or some other language? How does Python manage memory? Why doesn’t CPython use a more traditional garbage collection scheme? Why isn’t all memory freed when CPython exits? Why are there separate tuple and list data types? How are lists implemented in CPython? How are dictionaries implemented in CPython? Why must dictionary keys be immutable? Why doesn’t list.sort() return the sorted list? How do you specify and enforce an interface spec in Python? Why is there no goto? Why can’t raw strings (r-strings) end with a backslash? Why doesn’t Python have a “with” statement for attribute assignments? Why don’t generators support the with statement? Why are colons required for the if/while/def/class statements? Why does Python allow commas at the end of lists and tuples? Library and Extension FAQ General Library Questions Common tasks Threads Input and Output Network/Internet Programming Databases Mathematics and Numerics Extending/Embedding FAQ Can I create my own functions in C? Can I create my own functions in C++? Writing C is hard; are there any alternatives? How can I execute arbitrary Python statements from C? How can I evaluate an arbitrary Python expression from C? How do I extract C values from a Python object? How do I use Py_BuildValue() to create a tuple of arbitrary length? How do I call an object’s method from C? How do I catch the output from PyErr_Print() (or anything that prints to stdout/stderr)? How do I access a module written in Python from C? How do I interface to C++ objects from Python? I added a module using the Setup file and the make fails; why? How do I debug an extension? I want to compile a Python module on my Linux system, but some files are missing. Why? How do I tell “incomplete input” from “invalid input”? How do I find undefined g++ symbols __builtin_new or __pure_virtual? Can I create an object class with some methods implemented in C and others in Python (e.g. through inheritance)? Python on Windows FAQ How do I run a Python program under Windows? How do I make Python scripts executable? Why does Python sometimes take so long to start? How do I make an executable from a Python script? Is a *.pyd file the same as a DLL? How can I embed Python into a Windows application? How do I keep editors from inserting tabs into my Python source? How do I check for a keypress without blocking? How do I solve the missing api-ms-win-crt-runtime-l1-1-0.dll error? Graphic User Interface FAQ General GUI Questions What GUI toolkits exist for Python? Tkinter questions “Why is Python Installed on my Computer?” FAQ What is Python? Why is Python installed on my machine? Can I delete Python? Deprecations Pending removal in Python 3.15 Pending removal in Python 3.16 Pending removal in Python 3.17 Pending removal in Python 3.18 Pending removal in Python 3.19 Pending removal in future versions C API deprecations Pending removal in Python 3.15 Pending removal in Python 3.18 Pending removal in future versions Glossary About this documentation Contributors to the Python documentation Dealing with Bugs Documentation bugs Using the Python issue tracker Getting started contributing to Python yourself Copyright History and License History of the software Terms and conditions for accessing or otherwise using Python PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2 BEOPEN.COM LICENSE AGREEMENT FOR PYTHON 2.0 CNRI LICENSE AGREEMENT FOR PYTHON 1.6.1 CWI LICENSE AGREEMENT FOR PYTHON 0.9.0 THROUGH 1.2 ZERO-CLAUSE BSD LICENSE FOR CODE IN THE PYTHON DOCUMENTATION Licenses and Acknowledgements for Incorporated Software Mersenne Twister Sockets Asynchronous socket services Cookie management Execution tracing UUencode and UUdecode functions XML Remote Procedure Calls test_epoll Select kqueue SipHash24 strtod and dtoa OpenSSL expat libffi zlib cfuhash libmpdec W3C C14N test suite mimalloc asyncio Global Unbounded Sequences (GUS) Zstandard bindings © Copyright 2001 Python Software Foundation. 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