code: def connect_child_after(self, sprite, event, *args, **kwargs):
          
          handler = sprite.connect_after(event, *args, **kwargs)
          self._child_handlers[sprite].append(handler)
          return handler
docs: connect to a child event so that will disconnect if the child is
          removed from this sprite. this is the recommended way to connect to
          child events. syntax is same as for the .connect itself, just you
          prepend the child sprite as the first element