code: def send_signal(self, signal):
          
          if self.in_spectator_mode: return None
          logger.debug("Node %s broadcasts signal %s" % (self, signal))
          dispatcher.send(signal=signal, sender=self)
docs: Send signal from this node to all connected receivers unless the node is in spectator mode.
  
          signal -- (hashable) signal value, see `dispatcher` connect for details
  
          Return a list of tuple pairs [(receiver, response), ... ]
          or None if the node is in spectator mode.
  
          if any receiver raises an error, the error propagates back
          through send, terminating the dispatch loop, so it is quite
          possible to not have all receivers called if a raises an error.