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Python•Files, Modules, and the Standard Library

Python Python Built-in Modules

Flash cards

Review the key moves

1/3

Core idea

What is the main idea behind Python Python Built-in Modules?

Lesson checks

Practice each idea before moving on

Short Mimo-style checks built from this lesson's code, terms, and sequence.

1Quick choice

Which statement best captures the main point of this lesson?

2Order

Put the learning moves in the order that makes the concept easiest to apply.

These modules are available without extra installation (some are platform-dependent).

This page lists the built-in modules that ship with the Python 3.

Python Python Built-in Modules

This page lists the built-in modules that ship with the Python 3.13 Standard Library.

These modules are available without extra installation (some are platform-dependent).

A

Module	Description	Introduced
abc	Tools for defining Abstract Base Classes (interfaces for Python classes).	2.6
aifc	Read and write AIFF/AIFF-C audio files.	1.5.2
argparse	Parse command line arguments and create user-friendly CLIs.	2.7
array	Efficient arrays of basic numeric types (compact alternative to lists).	1.0
ast	Work with Python code as an Abstract Syntax Tree (analyze or transform code).	2.6
asyncio	Write concurrent code using the async/await syntax (event loop, tasks, IO).	3.4
atexit	Register functions to run automatically when the program exits.	2.0

B

Module	Description	Introduced
base64	Encode and decode data using Base16, Base32, Base64, etc.	2.0
bdb	Debugger framework used by pdb (implements the core debugging logic).	-
binascii	Convert between binary and ASCII (hex, base64 helpers at C speed).	2.0
bisect	Maintain sorted lists; insert and search with binary search.	2.0
builtins	Access Python's built-in objects like len, range, and exceptions.	3.0
bz2	Read and write bzip2-compressed files and streams.	2.3

C

Module	Description	Introduced
calendar	Work with dates as calendars; print text calendars and compute month info.	2.0
cgi	Helpers for Common Gateway Interface (legacy web server scripts).	2.0
cgitb	Pretty tracebacks for CGI scripts (HTML formatted error reports).	-
cmd	Build simple line-oriented command interpreters (REPL-like shells).	2.0
code	Run an interactive interpreter or embed one in your program.	2.0
codecs	Text encodings and decoding/encoding helpers.	2.0
codeop	Compile Python code objects conditionally (used by code editors and shells).	2.0
collections	High-performance container datatypes like deque, Counter, namedtuple.	2.4
colorsys	Convert between color systems: RGB, YIQ, HLS, HSV.	2.0
concurrent	Concurrency framework (futures) for running callables asynchronously.	3.2
configparser	Read and write INI-style configuration files.	3.0
contextlib	Utilities for context managers and the with-statement.	2.5
contextvars	Context-local storage for async code (like thread-local, but for tasks).	3.7
copy	Shallow and deep copy operations for Python objects.	2.0
copyreg	Register custom pickling functions for complex objects.	3.0
csv	Read and write CSV files (comma-separated values) with ease.	2.3
ctypes	Call C libraries and work with C-compatible data types.	2.5
curses	Terminal handling for character-cell UIs (Unix-like systems only).	2.0

D

Module	Description	Introduced
dataclasses	Decorator and helpers for classes that store data (auto-generate init, repr, etc.).	3.7
datetime	Dates, times, time zones, and timedeltas made simple and precise.	2.3
dbm	Family of simple on-disk key/value databases (backed by platform libs).	2.0
decimal	Fixed-point and floating decimal arithmetic for money and exact math.	2.4
difflib	Compare sequences and create human-readable diffs.	2.1
dis	Disassemble Python bytecode for inspection and debugging.	2.0
doctest	Test examples embedded in docstrings (keeps docs and code in sync).	2.1

E

Module	Description	Introduced
email	Parse, build, and send email messages (headers, MIME, attachments).	2.2
encodings	Implementation of text encodings used by Python's codec system.	2.0
ensurepip	Bootstraps pip into a Python installation.	3.4
enum	Define enumerations (named constants) with nice semantics.	3.4
errno	Standard error number constants from the OS.	2.0

F

Module	Description	Introduced
faulthandler	Dump Python tracebacks on a crash or on demand (helps debug hard faults).	3.3
filecmp	Compare files and directories to see what changed.	2.0
fileinput	Loop over lines from stdin or a list of files as a single stream.	2.0
fnmatch	Match filenames using shell-style wildcards.	2.0
fractions	Rational numbers (Fractions) for exact arithmetic.	2.6
ftplib	FTP client library for transferring files.	2.0
functools	Higher-order functions and utilities (lru_cache, partial, wraps, etc.).	2.5

G

Module	Description	Introduced
gc	Control the garbage collector and inspect tracked objects.	2.0
getopt	Parse command-line options (POSIX-style).	1.5.2
getpass	Prompt for a password without echoing it to the console.	2.0
gettext	Internationalization (i18n) support for translating messages.	2.3
glob	Find pathnames matching a pattern like *.py.	2.0
graphlib	Topological sorting utilities for dependency graphs.	3.9
gzip	Read and write gzip-compressed files and streams.	2.0

H

Module	Description	Introduced
hashlib	Secure hashes and message digests (SHA, MD5, BLAKE2, etc.).	2.5
heapq	Heap queue (priority queue) algorithms on plain lists.	2.3
hmac	Keyed-hash message authentication codes (HMAC).	2.2
html	HTML helpers (escape/unescape text).	3.2
http	HTTP modules package (client, server, cookies).	3.0

I

Module	Description	Introduced
idlelib	Support for the IDLE interactive Python environment.	-
imaplib	IMAP4 client library for accessing email servers.	2.0
imghdr	Determine the type of an image file.	2.0
imp	Access the import internals (deprecated; use importlib ).	-
importlib	Programmatic interface to Python's import mechanism.	3.1
inspect	Inspect live objects such as modules, classes, and functions.	-
io	Input/Output streams and buffering (text and binary).	2.6

J

Module	Description	Introduced
json	Encode and decode JSON data (JavaScript Object Notation).	2.6

K

Module	Description	Introduced
keyword	Test for Python keywords; list all keywords.	-

L

Module	Description	Introduced
linecache	Read text lines from files with random access.	2.0
locale	Internationalization (i18n) support for formatting numbers and dates.	2.0
logging	Flexible event logging system with various handlers.	2.3
lzma	Compression using the LZMA algorithm (xz format).	3.3

M

Module	Description	Introduced
mailbox	Work with various mailbox formats (mbox, Maildir, etc.).	2.3
mailcap	Read mailcap files (MIME handlers configuration).	2.0
marshal	Read and write Python values in a binary format (for .pyc internals).	-
math	Fast math functions: trigonometry, logarithms, constants, etc.	-
mimetypes	Guess a file's type based on its filename or URL.	2.0
mmap	Memory-map files for efficient random access.	2.0
modulefinder	Find modules used by a script (dependency scanning).	-
msilib	Create and read Microsoft Installer (.msi) files (Windows only).	-
msvcrt	Access to Microsoft C runtime routines (Windows only).	-
multiprocessing	Run code in parallel using processes (bypass the GIL).	2.6

N

Module	Description	Introduced
netrc	Parse .netrc files for machine login credentials.	2.0
nntplib	Client for NNTP (Usenet) news servers.	2.0
numbers	Abstract base classes for numeric types.	2.6
nis	Interface to Sun's NIS (Yellow Pages) service (Unix platforms).	-
ntpath	Windows path operations (used by os.path on Windows).	2.0

O

Module	Description	Introduced
operator	Functional interface to operators (add, mul, itemgetter, attrgetter).	1.5.2
optparse	Deprecated parser for command line options (use argparse).	2.3
os	Operating system interfaces: files, environment, processes.	-

P

Module	Description	Introduced
pathlib	Object-oriented filesystem paths.	3.4
pdb	Interactive debugger for Python programs.	2.0
pickle	Serialize and deserialize Python objects (not secure against untrusted data).	2.0
pickletools	Tools for analyzing pickled data.	2.3
pipes	Pipe shell commands together (Unix).	2.0
pkgutil	Utilities for packages: walk packages, find loaders, etc.	2.3
platform	Access to underlying platform information.	2.3
plistlib	Read and write Apple .plist files.	2.6
poplib	POP3 email client.	2.0
posix	POSIX APIs (Unix-only, low-level).	2.0
pprint	Pretty-print Python data structures.	2.0
profile	Deterministic profiling of Python programs.	2.0
pstats	Work with profiling results produced by profile/cProfile.	2.0
pty	Pseudo-terminal utilities (Unix).	2.0
pyclbr	Read module to get class browser information without importing it.	2.0
pydoc	Generate and view Python documentation.	2.1
py_compile	Compile Python source files to bytecode.	2.0

Q

Module	Description	Introduced
queue	Thread-safe FIFO/LIFO/priority queues.	2.6
quopri	Encode/decode MIME quoted-printable data.	2.0

R

Module	Description	Introduced
random	Generate pseudo-random numbers for various distributions.	2.0
re	Regular expression operations for pattern matching in strings.	2.0
reprlib	Safe string representations for large or recursive structures.	3.0
resource	Control and query system resource limits (Unix).	2.0
rlcompleter	Tab-completion support for the interactive interpreter.	2.0
runpy	Run modules as scripts (like python -m).	2.5

S

Module	Description	Introduced
sched	Event scheduler for running functions at specific times.	2.0
secrets	Generate cryptographically strong random numbers and tokens.	3.6
select	Low-level I/O multiplexing (select, poll, epoll, kqueue).	2.0
selectors	High-level I/O multiplexing built on select module.	3.4
shelve	Simple persistent storage for Python objects (dict-like API).	2.0
shlex	Parse shell-like syntaxes into tokens.	2.0
shutil	High-level file operations: copy, move, archive, disk usage.	2.0
signal	Set handlers for asynchronous signals.	2.0
site	Site-specific configuration hook that runs at startup.	2.0
smtplib	Send emails using the SMTP protocol.	2.0
socket	Low-level networking interface.	2.0
socketserver	Framework for network servers (TCP/UDP).	3.0
sqlite3	Built-in lightweight SQL database (SQLite).	2.5
ssl	TLS/SSL wrapper for secure network connections.	2.6
stat	Constants and helpers for interpreting os.stat() results.	2.0
statistics	Basic statistics (mean, median, stdev).	3.4
string	Common string constants and helpers.	2.0
stringprep	String preparation for internet protocols (IDNA).	2.3
struct	Convert between Python values and C structs packed as bytes.	2.0
subprocess	Spawn new processes and connect to their input/output/error pipes.	2.4
sunau	Read and write Sun AU audio files.	2.0
symtable	Access the compiler's internal symbol tables.	2.6
sys	Access to interpreter variables and functions.	-
sysconfig	Access Python's configuration information.	3.2

T

Module	Description	Introduced
tabnanny	Detect ambiguous indentation in Python source files.	2.0
tarfile	Read and write tar archives, including gzip/bz2/xz.	2.3
telnetlib	Telnet client implementation.	2.0
tempfile	Create temporary files and directories safely.	2.0
termios	POSIX terminal control (Unix).	2.0
test	Regression tests package for the Python standard library.	2.0
textwrap	Wrap and fill text paragraphs.	2.3
threading	Higher-level threading interface (locks, events, threads).	2.0
time	Time access and conversions.	-
timeit	Measure execution time of small code snippets.	2.3
tkinter	Standard GUI toolkit (Tk interface) package.	3.0
token	Token constants used by the Python tokenizer.	2.0
tokenize	Turn Python source into tokens (lexical scanner).	2.0
tomllib	Read TOML files into Python data structures.	3.11
trace	Trace program execution and produce coverage reports.	2.0
traceback	Print or retrieve stack traces.	2.0
tracemalloc	Track memory allocations to find leaks and hotspots.	3.4
tty	Terminal control functions (Unix).	2.0
turtle	Simple graphics library for teaching and fun.	2.5
types	Names for built-in types and helper factories.	2.0
typing	Type hints and typing helpers for static analysis and tooling.	3.5

U

Module	Description	Introduced
unicodedata	Access the Unicode Character Database (properties, normalization).	2.0
unittest	Unit testing framework (xUnit style) for Python.	2.1
urllib	Package for working with URLs (requests, parsing, robots).	2.0
uuid	Generate universally unique identifiers (UUIDs).	2.5

V

Module	Description	Introduced
venv	Create lightweight isolated Python environments.	3.3

W

Module	Description	Introduced
warnings	Issue and control warning messages.	2.0
wave	Read and write WAV audio files.	2.0
weakref	Weak references to objects (avoid reference cycles).	2.0
webbrowser	Open URLs in a web browser.	2.0
wsgiref	WSGI utilities and simple reference server for web apps.	2.3

Python File Open

How to Remove Duplicates From a Python List

Loading lesson path

Python•Files, Modules, and the Standard Library

Python Python Built-in Modules

Flash cards

Review the key moves

1/3

Core idea

What is the main idea behind Python Python Built-in Modules?

Lesson checks

Practice each idea before moving on

Short Mimo-style checks built from this lesson's code, terms, and sequence.

1Quick choice

Which statement best captures the main point of this lesson?

2Order

Put the learning moves in the order that makes the concept easiest to apply.

These modules are available without extra installation (some are platform-dependent).

This page lists the built-in modules that ship with the Python 3.

Python Python Built-in Modules

This page lists the built-in modules that ship with the Python 3.13 Standard Library.

These modules are available without extra installation (some are platform-dependent).

A

Module	Description	Introduced
abc	Tools for defining Abstract Base Classes (interfaces for Python classes).	2.6
aifc	Read and write AIFF/AIFF-C audio files.	1.5.2
argparse	Parse command line arguments and create user-friendly CLIs.	2.7
array	Efficient arrays of basic numeric types (compact alternative to lists).	1.0
ast	Work with Python code as an Abstract Syntax Tree (analyze or transform code).	2.6
asyncio	Write concurrent code using the async/await syntax (event loop, tasks, IO).	3.4
atexit	Register functions to run automatically when the program exits.	2.0

B

Module	Description	Introduced
base64	Encode and decode data using Base16, Base32, Base64, etc.	2.0
bdb	Debugger framework used by pdb (implements the core debugging logic).	-
binascii	Convert between binary and ASCII (hex, base64 helpers at C speed).	2.0
bisect	Maintain sorted lists; insert and search with binary search.	2.0
builtins	Access Python's built-in objects like len, range, and exceptions.	3.0
bz2	Read and write bzip2-compressed files and streams.	2.3

C

Module	Description	Introduced
calendar	Work with dates as calendars; print text calendars and compute month info.	2.0
cgi	Helpers for Common Gateway Interface (legacy web server scripts).	2.0
cgitb	Pretty tracebacks for CGI scripts (HTML formatted error reports).	-
cmd	Build simple line-oriented command interpreters (REPL-like shells).	2.0
code	Run an interactive interpreter or embed one in your program.	2.0
codecs	Text encodings and decoding/encoding helpers.	2.0
codeop	Compile Python code objects conditionally (used by code editors and shells).	2.0
collections	High-performance container datatypes like deque, Counter, namedtuple.	2.4
colorsys	Convert between color systems: RGB, YIQ, HLS, HSV.	2.0
concurrent	Concurrency framework (futures) for running callables asynchronously.	3.2
configparser	Read and write INI-style configuration files.	3.0
contextlib	Utilities for context managers and the with-statement.	2.5
contextvars	Context-local storage for async code (like thread-local, but for tasks).	3.7
copy	Shallow and deep copy operations for Python objects.	2.0
copyreg	Register custom pickling functions for complex objects.	3.0
csv	Read and write CSV files (comma-separated values) with ease.	2.3
ctypes	Call C libraries and work with C-compatible data types.	2.5
curses	Terminal handling for character-cell UIs (Unix-like systems only).	2.0

D

Module	Description	Introduced
dataclasses	Decorator and helpers for classes that store data (auto-generate init, repr, etc.).	3.7
datetime	Dates, times, time zones, and timedeltas made simple and precise.	2.3
dbm	Family of simple on-disk key/value databases (backed by platform libs).	2.0
decimal	Fixed-point and floating decimal arithmetic for money and exact math.	2.4
difflib	Compare sequences and create human-readable diffs.	2.1
dis	Disassemble Python bytecode for inspection and debugging.	2.0
doctest	Test examples embedded in docstrings (keeps docs and code in sync).	2.1

E

Module	Description	Introduced
email	Parse, build, and send email messages (headers, MIME, attachments).	2.2
encodings	Implementation of text encodings used by Python's codec system.	2.0
ensurepip	Bootstraps pip into a Python installation.	3.4
enum	Define enumerations (named constants) with nice semantics.	3.4
errno	Standard error number constants from the OS.	2.0

F

Module	Description	Introduced
faulthandler	Dump Python tracebacks on a crash or on demand (helps debug hard faults).	3.3
filecmp	Compare files and directories to see what changed.	2.0
fileinput	Loop over lines from stdin or a list of files as a single stream.	2.0
fnmatch	Match filenames using shell-style wildcards.	2.0
fractions	Rational numbers (Fractions) for exact arithmetic.	2.6
ftplib	FTP client library for transferring files.	2.0
functools	Higher-order functions and utilities (lru_cache, partial, wraps, etc.).	2.5

G

Module	Description	Introduced
gc	Control the garbage collector and inspect tracked objects.	2.0
getopt	Parse command-line options (POSIX-style).	1.5.2
getpass	Prompt for a password without echoing it to the console.	2.0
gettext	Internationalization (i18n) support for translating messages.	2.3
glob	Find pathnames matching a pattern like *.py.	2.0
graphlib	Topological sorting utilities for dependency graphs.	3.9
gzip	Read and write gzip-compressed files and streams.	2.0

H

Module	Description	Introduced
hashlib	Secure hashes and message digests (SHA, MD5, BLAKE2, etc.).	2.5
heapq	Heap queue (priority queue) algorithms on plain lists.	2.3
hmac	Keyed-hash message authentication codes (HMAC).	2.2
html	HTML helpers (escape/unescape text).	3.2
http	HTTP modules package (client, server, cookies).	3.0

I

Module	Description	Introduced
idlelib	Support for the IDLE interactive Python environment.	-
imaplib	IMAP4 client library for accessing email servers.	2.0
imghdr	Determine the type of an image file.	2.0
imp	Access the import internals (deprecated; use importlib ).	-
importlib	Programmatic interface to Python's import mechanism.	3.1
inspect	Inspect live objects such as modules, classes, and functions.	-
io	Input/Output streams and buffering (text and binary).	2.6

J

Module	Description	Introduced
json	Encode and decode JSON data (JavaScript Object Notation).	2.6

K

Module	Description	Introduced
keyword	Test for Python keywords; list all keywords.	-

L

Module	Description	Introduced
linecache	Read text lines from files with random access.	2.0
locale	Internationalization (i18n) support for formatting numbers and dates.	2.0
logging	Flexible event logging system with various handlers.	2.3
lzma	Compression using the LZMA algorithm (xz format).	3.3

M

Module	Description	Introduced
mailbox	Work with various mailbox formats (mbox, Maildir, etc.).	2.3
mailcap	Read mailcap files (MIME handlers configuration).	2.0
marshal	Read and write Python values in a binary format (for .pyc internals).	-
math	Fast math functions: trigonometry, logarithms, constants, etc.	-
mimetypes	Guess a file's type based on its filename or URL.	2.0
mmap	Memory-map files for efficient random access.	2.0
modulefinder	Find modules used by a script (dependency scanning).	-
msilib	Create and read Microsoft Installer (.msi) files (Windows only).	-
msvcrt	Access to Microsoft C runtime routines (Windows only).	-
multiprocessing	Run code in parallel using processes (bypass the GIL).	2.6

N

Module	Description	Introduced
netrc	Parse .netrc files for machine login credentials.	2.0
nntplib	Client for NNTP (Usenet) news servers.	2.0
numbers	Abstract base classes for numeric types.	2.6
nis	Interface to Sun's NIS (Yellow Pages) service (Unix platforms).	-
ntpath	Windows path operations (used by os.path on Windows).	2.0

O

Module	Description	Introduced
operator	Functional interface to operators (add, mul, itemgetter, attrgetter).	1.5.2
optparse	Deprecated parser for command line options (use argparse).	2.3
os	Operating system interfaces: files, environment, processes.	-

P

Module	Description	Introduced
pathlib	Object-oriented filesystem paths.	3.4
pdb	Interactive debugger for Python programs.	2.0
pickle	Serialize and deserialize Python objects (not secure against untrusted data).	2.0
pickletools	Tools for analyzing pickled data.	2.3
pipes	Pipe shell commands together (Unix).	2.0
pkgutil	Utilities for packages: walk packages, find loaders, etc.	2.3
platform	Access to underlying platform information.	2.3
plistlib	Read and write Apple .plist files.	2.6
poplib	POP3 email client.	2.0
posix	POSIX APIs (Unix-only, low-level).	2.0
pprint	Pretty-print Python data structures.	2.0
profile	Deterministic profiling of Python programs.	2.0
pstats	Work with profiling results produced by profile/cProfile.	2.0
pty	Pseudo-terminal utilities (Unix).	2.0
pyclbr	Read module to get class browser information without importing it.	2.0
pydoc	Generate and view Python documentation.	2.1
py_compile	Compile Python source files to bytecode.	2.0

Q

Module	Description	Introduced
queue	Thread-safe FIFO/LIFO/priority queues.	2.6
quopri	Encode/decode MIME quoted-printable data.	2.0

R

Module	Description	Introduced
random	Generate pseudo-random numbers for various distributions.	2.0
re	Regular expression operations for pattern matching in strings.	2.0
reprlib	Safe string representations for large or recursive structures.	3.0
resource	Control and query system resource limits (Unix).	2.0
rlcompleter	Tab-completion support for the interactive interpreter.	2.0
runpy	Run modules as scripts (like python -m).	2.5

S

Module	Description	Introduced
sched	Event scheduler for running functions at specific times.	2.0
secrets	Generate cryptographically strong random numbers and tokens.	3.6
select	Low-level I/O multiplexing (select, poll, epoll, kqueue).	2.0
selectors	High-level I/O multiplexing built on select module.	3.4
shelve	Simple persistent storage for Python objects (dict-like API).	2.0
shlex	Parse shell-like syntaxes into tokens.	2.0
shutil	High-level file operations: copy, move, archive, disk usage.	2.0
signal	Set handlers for asynchronous signals.	2.0
site	Site-specific configuration hook that runs at startup.	2.0
smtplib	Send emails using the SMTP protocol.	2.0
socket	Low-level networking interface.	2.0
socketserver	Framework for network servers (TCP/UDP).	3.0
sqlite3	Built-in lightweight SQL database (SQLite).	2.5
ssl	TLS/SSL wrapper for secure network connections.	2.6
stat	Constants and helpers for interpreting os.stat() results.	2.0
statistics	Basic statistics (mean, median, stdev).	3.4
string	Common string constants and helpers.	2.0
stringprep	String preparation for internet protocols (IDNA).	2.3
struct	Convert between Python values and C structs packed as bytes.	2.0
subprocess	Spawn new processes and connect to their input/output/error pipes.	2.4
sunau	Read and write Sun AU audio files.	2.0
symtable	Access the compiler's internal symbol tables.	2.6
sys	Access to interpreter variables and functions.	-
sysconfig	Access Python's configuration information.	3.2

T

Module	Description	Introduced
tabnanny	Detect ambiguous indentation in Python source files.	2.0
tarfile	Read and write tar archives, including gzip/bz2/xz.	2.3
telnetlib	Telnet client implementation.	2.0
tempfile	Create temporary files and directories safely.	2.0
termios	POSIX terminal control (Unix).	2.0
test	Regression tests package for the Python standard library.	2.0
textwrap	Wrap and fill text paragraphs.	2.3
threading	Higher-level threading interface (locks, events, threads).	2.0
time	Time access and conversions.	-
timeit	Measure execution time of small code snippets.	2.3
tkinter	Standard GUI toolkit (Tk interface) package.	3.0
token	Token constants used by the Python tokenizer.	2.0
tokenize	Turn Python source into tokens (lexical scanner).	2.0
tomllib	Read TOML files into Python data structures.	3.11
trace	Trace program execution and produce coverage reports.	2.0
traceback	Print or retrieve stack traces.	2.0
tracemalloc	Track memory allocations to find leaks and hotspots.	3.4
tty	Terminal control functions (Unix).	2.0
turtle	Simple graphics library for teaching and fun.	2.5
types	Names for built-in types and helper factories.	2.0
typing	Type hints and typing helpers for static analysis and tooling.	3.5

U

Module	Description	Introduced
unicodedata	Access the Unicode Character Database (properties, normalization).	2.0
unittest	Unit testing framework (xUnit style) for Python.	2.1
urllib	Package for working with URLs (requests, parsing, robots).	2.0
uuid	Generate universally unique identifiers (UUIDs).	2.5

V

Module	Description	Introduced
venv	Create lightweight isolated Python environments.	3.3

W

Module	Description	Introduced
warnings	Issue and control warning messages.	2.0
wave	Read and write WAV audio files.	2.0
weakref	Weak references to objects (avoid reference cycles).	2.0
webbrowser	Open URLs in a web browser.	2.0
wsgiref	WSGI utilities and simple reference server for web apps.	2.3

Python File Open

How to Remove Duplicates From a Python List