def use_pure_python():
global BitString, _using_numpy<EOL>from ._python_bitstrings import BitString<EOL>_using_numpy = False<EOL>
Force the package to use the pure Python BitString implementation.
    IMPORTANT: Bitstrings of different implementations cannot be mixed.
    Attempting to do so will result in undefined behavior.

    Usage:
        use_pure_python()
        assert not using_numpy()

    Arguments: None
    Return: None