def restore_tag_name(tag_name: str) -> str:
    """Reverts the function :py:func:`xml_tag_name`::

    >>> restore_tag_name('ANONYMOUS_Series__')
    ':Series'
    """
    if tag_name[-2:] == "__" and tag_name[:10] == "ANONYMOUS_":
        return ':' + tag_name[10:-2]
    return tag_name