Overrides default handling to use the global shared zone group state
        cache, unless another cache is specified.

def GetZoneGroupState(self, *args, **kwargs):
        """Overrides default handling to use the global shared zone group state
        cache, unless another cache is specified."""
        kwargs['cache'] = kwargs.get('cache', zone_group_state_shared_cache)
        return self.send_command('GetZoneGroupState', *args, **kwargs)