text: """
      Slixmpp: The Slick XMPP Library
      Copyright (C) 2012  Nathanael C. Fritz
      This file is part of Slixmpp.
  
      See the file LICENSE for copying permission.
  """
  
  import logging
  
  from slixmpp.stanza import StreamFeatures
  from slixmpp.features.feature_rosterver import stanza
  from slixmpp.xmlstream import register_stanza_plugin
  from slixmpp.plugins.base import BasePlugin
  
  
  log = logging.getLogger(__name__)
  
  
  class FeatureRosterVer(BasePlugin):
  
      name = 'feature_rosterver'
      description = 'RFC 6121: Stream Feature: Roster Versioning'
      dependences = set()
      stanza = stanza
  
      def plugin_init(self):
          self.xmpp.register_feature('rosterver',
                  self._handle_rosterver,
                  restart=False,
                  order=9000)
  
          register_stanza_plugin(StreamFeatures, stanza.RosterVer)
  
      def _handle_rosterver(self, features):
          """Enable using roster versioning.
  
          Arguments:
              features -- The stream features stanza.
          """
          log.debug("Enabling roster versioning.")
          self.xmpp.features.add('rosterver')
  