code: def unregister_message_handler(self, target_or_handler):
          
          if isinstance(target_or_handler, str):
              del self._message_handlers[target_or_handler]
          else:
              for key, val in self._message_handlers.items():
                  if val == target_or_handler:
                      del self._message_handlers[key]
docs: Unregister a mpv script message handler for the given script message target name.
  
          You can also call the ``unregister_mpv_messages`` function attribute set on the handler function when it is
          registered.