docs: def sender(self, func, routing=None, routing_re=None):
          """
          Registers a sender function
          """
          if routing and not isinstance(routing, list):
              routing = [routing]
  
          if routing_re:
              if not isinstance(routing_re, list):
                  routing_re = [routing_re]
              routing_re[:] = [re.compile(r) for r in routing_re]
  
          self.senders.append((func, routing, routing_re))