'Process the session_start event.
Typical actions for the session_start event are
requesting the roster and broadcasting an initial
presence stanza.
Arguments:
event -- An empty dictionary. The session_start
event does not provide any additional
data.'

def start(self, event):

    self.send_presence()
    self.get_roster()
    print 'Start    MAM'
    ret = self['xep_0313'].get_preferences()
    print ('Archiving    default    is:    ', ret['mam_prefs']['default'])
    answer = self['xep_0313'].retrieve(block=True, callback=None, number_of_queried_elements=1, collect_all=True)
    self.__handle_mam_result(answer)
    print 'End    MAM'
