docs: def _store_cached_zone_variable(self, zone_id, name, value):
          """
          Stores the current known value of a zone variable into the cache.
          Calls any zone callbacks.
          """
          zone_state = self._zone_state.setdefault(zone_id, {})
          name = name.lower()
          zone_state[name] = value
          logger.debug("Zone Cache store %s.%s = %s",
                       zone_id.device_str(), name, value)
          for callback in self._zone_callbacks:
              callback(zone_id, name, value)