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.

This is a backport of the standard library typing module to Python
versions older than 3.5.

Homepage:
https://docs.python.org/3/library/typing.html
