code: def partymode(self):
          
          # Tell every other visible zone to join this one
          # pylint: disable = expression-not-assigned
          [zone.join(self) for zone in self.visible_zones if zone is not self]
docs: Put all the speakers in the network in the same group, a.k.a Party
          Mode.
  
          This blog shows the initial research responsible for this:
          http://blog.travelmarx.com/2010/06/exploring-sonos-via-upnp.html
  
          The trick seems to be (only tested on a two-speaker setup) to tell each
          speaker which to join. There's probably a bit more to it if multiple
          groups have been defined.