This is a backport of the standard library typing module to Python
versions older than 3.5.
Typing defines a standard notation for Python function and variable type
annotations. The notation can be used for documenting code in a concise,
standard format, and it has been designed to also be used by static and
runtime type checkers, static analyzers, IDEs and other tools.

WWW: https://pypi.python.org/pypi/typing