code: def send(self, sender, **named):
          
          responses = []
          if not self.receivers:
              return responses
  
          sender_id = _make_id(sender)
          if sender_id not in self.sender_status:
              self.sender_status[sender_id] = {}
  
          if self.sender_status[sender_id] == named:
              return responses
  
          self.sender_status[sender_id] = named
  
          for receiver in self._live_receivers(sender_id):
              response = receiver(signal=self, sender=sender, **named)
              responses.append((receiver, response))
          return responses
docs: Send signal from sender to all connected receivers *only if* the signal's
          contents has changed.
  
          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.
  
          Arguments:
  
              sender
                  The sender of the signal Either a specific object or None.
  
              named
                  Named arguments which will be passed to receivers.
  
          Returns a list of tuple pairs [(receiver, response), ... ].