The documentation at https://docs.python.org/3/library/functions.html#locals https://docs.python.org/3/library/functions.html#locals doesn't indicate that local

The documentation at https://docs.python.org/3/library/functions.html#locals https://docs.python.org/3/library/functions.html#locals doesn't indicate that locals is not part of the language - where is it documented that using it is a hack and that python implementations need not support it?