Get a list of existing :class:`language_tags.Subtag.Subtag` objects given the input subtag(s).

        :param subtags: string subtag or list of string subtags.
        :return: a list of existing :class:`language_tags.Subtag.Subtag` objects. The return list can be empty.

def subtags(subtags):
        """
        Get a list of existing :class:`language_tags.Subtag.Subtag` objects given the input subtag(s).

        :param subtags: string subtag or list of string subtags.
        :return: a list of existing :class:`language_tags.Subtag.Subtag` objects. The return list can be empty.
        """
        result = []

        if not isinstance(subtags, list):
            subtags = [subtags]

        for subtag in subtags:
            for type in tags.types(subtag):
                result.append(Subtag(subtag, type))

        return result