def get_import_for_type(t):
    """given a type, return a tuple of the (module-path, type_name)
    or (None, None) if it is a built in."""
    t_as_string = to_str(t)
    if not is_identifier(t_as_string):
        # this class expanded into something other than a single identifier
        # we can ignore it.  This is the case when we encounter something
        # like the configman.converter.str_to_classes_in_namespaces
        # InnerClassList.  We can safely ignore these things here.
        return (None, None)
    if '.' in t_as_string:
        parts = t_as_string.split('.')
        return ('.'.join(parts[:-1]), parts[-1])
    else:
        if t_as_string in known_mapping_str_to_type:
            return (None, None)
        return (None, t_as_string)