The Python runtime does not enforce function and variable type annotations. They can be used by third party tools such as type checkers, IDEs, linters, etc. This module provides runtime …

Optional[...] is a shorthand notation for Union[..., None], telling the type checker that either an object of the specific type is required, or None is required. ... stands for any valid type hint, …

The following grammar describes the allowed elements of type and annotation expressions: | <NotRequired> '[' annotation_expression ']' | <ReadOnly> '[' annotation_expression ']' | …

This PEP proposes overloading the | operator on types to allow writing Union[X, Y] as X | Y, and allows it to appear in isinstance and issubclass calls. PEP 484 and PEP 526 propose a …

From Python 3.10 onwards, PEP 604 introduces the | operator as a concise alternative to Union, simplifying syntax for type annotations. This is an example of a function using type hints: …

If the dynamic typing is needed, use Union (pre-Python 3.10, imported from typing) or the pipe operator, | (Python 3.10+): from typing import Union # not required Python 3.10+. dynamic: …

Since Python 3.10, you can use the | operator: Specifies multiple possible types for a variable. Since Python 3.10, use | instead of Union: Used to define custom type names for readability. …

Since Python version 3.10, Unions can be writte as X | Y which is equivalent to Union[X, Y]. Is there some way/workaround to easily use (or just ignore) the X | Y syntax on Python 3.9? I …

In Python 3.10, you no longer need to import Union at all. All the details are in PEP 604. The PEP allows you to replace it entirely with the | operator. Once you have done that, the code above …

Type annotations — also known as type signatures — are used to indicate the datatypes of variables and input/outputs of functions and methods. In many languages, datatypes are …