Function NotRequired

Lib/typing.py:3436–3451

Special typing construct to mark a TypedDict key as potentially missing. For example:: class Movie(TypedDict): title: str year: NotRequired[int] m = Movie( title='The Matrix', # typechecker error if key is omitted year=1999,

(self, parameters)

@_SpecialForm
def NotRequired(self, parameters):
    """Special typing construct to mark a TypedDict key as potentially missing.

    For example::

        class Movie(TypedDict):
            title: str
            year: NotRequired[int]

        m = Movie(
            title='The Matrix',  # typechecker error if key is omitted
            year=1999,
        )
    """
    item = _type_check(parameters, f'{self._name} accepts only a single type.')
    return _GenericAlias(self, (item,))


@_SpecialForm