def native_string_to_bytes(s, encoding='ascii', errors='strict'):
    """
    Ensure that the native string ``s`` is converted to ``bytes``.
    """
    if not isinstance(s, str):
        raise TypeError('{} must be type str, not {}'.format(s, type(s)))
    if str is bytes:
        return s
    else:
        return s.encode(encoding=encoding, errors=errors)
