Turn input into a native string if possible.

def str_if_nested_or_str(s):
    """Turn input into a native string if possible."""
    if isinstance(s, ALL_STRING_TYPES):
        return str(s)
    if isinstance(s, (list, tuple)):
        return type(s)(map(str_if_nested_or_str, s))
    if isinstance(s, (dict, )):
        return stringify_dict_contents(s)
    return s