docs: def activate_output(self, universe: int) -> None:
          """
          Activates a universe that's then starting to sending every second.
          See http://tsp.esta.org/tsp/documents/docs/E1-31-2016.pdf for more information
          :param universe: the universe to activate
          """
          check_universe(universe)
          # check, if the universe already exists in the list:
          if universe in self._outputs:
              return
          # add new sending:
          new_output = Output(DataPacket(cid=self.__CID, sourceName=self.source_name, universe=universe))
          self._outputs[universe] = new_output