'Add a stanza object class as a known root stanza.
A root stanza is one that appears as a direct child of the stream\'s
root element.
Stanzas that appear as substanzas of a root stanza do not need to
be registered here. That is done using register_stanza_plugin() from
sleekxmpp.xmlstream.stanzabase.
Stanzas that are not registered will not be converted into
stanza objects, but may still be processed using handlers and
matchers.
:param stanza_class: The top-level stanza object\'s class.'

def register_stanza(self, stanza_class):

    self.__root_stanza.append(stanza_class)
