function and method parameters, return values,
 and variables.

The value should be a positional-only string literal to allow static tools
like editors and documentation generators to use it.

This complements docstrings.

The string value passed is available in the attribute ``documentation``.

Example::

    >>> from typing_extensions import Annotated, Doc
    >>> def hi(to: Annotated[str, Doc("Who to say hi to")]) -> None: ...
Ú
documentationr~