A registry of features supported by the from __future__ compiler directive.difflib

Tools to detect differences and calculate deltas between lists of objects.distutils (package)

Tools to distribute and install Python extensions.doctest

A test framework, based on docstrings. To use this for general testing, you can write test scripts and use doctest to make sure the test scripts work as documented. Also see unittest.inspect

Tools to extract information about Python objects, of all kinds.pydoc

Tools to automatically generate documentation for a Python module, based on class layout, function and method signatures, docstrings, and more.smtpd

A simple SMTP proxy daemon.symtable

Tools to access the compiler’s internal symbol table.ucnhash (removed)

Unicode name database, used to support \N{} escapes in Unicode string literals. The database has been moved to the unicodedata module.unit.

A warning generation framework. The standard library itself uses this framework to generate warnings for deprecated library modules.weakref

Helpers to create weak object references, including weak containers.xml.dom.domreg

XML DOM implementation registry. To access the registry, use the xml.dom.getDOMImplementation and xml.dom.registerDOMImplementation functions.xreadlines

A file wrapper that uses large buffers to speed up reading individual text line