'Return the namespaced name of the stanza\'s root element.
The format for the tag name is::
\'{namespace}elementname\'
For example, for the stanza ``<foo xmlns="bar" />``,
``stanza.tag_name()`` would return ``"{bar}foo"``.'

@classmethod
def tag_name(cls):

    return (u'{%s}%s' % (cls.namespace, cls.name))
