code: def new_cast_status(self, cast_status):
          
          casts = self._casts
          group_members = self._mz.members
          for member_uuid in group_members:
              if member_uuid not in casts:
                  continue
              for listener in list(casts[member_uuid]['listeners']):
                  listener.multizone_new_cast_status(
                      self._group_uuid, cast_status)
docs: Handle reception of a new CastStatus.