## Feature Since CPython 3.10 version, it became to allow writing union types as `X | Y` (e.g. `int | str`). ## Python Documentation - https://www.python.org/dev/peps/pep-0604/ - https://github.com/python/cpython/blob/a4774f42e35861c4bb16928cffb011c2d8a285ac/Objects/unionobject.c - https://github.com/python/cpython/blob/2c045bd5673d56c3fdde7536da9df1c7d6f270f0/Objects/typeobject.c#L4359-L4361