code: def write_message(
          self, message: Union[str, bytes], binary: bool = False
      ) -> "Future[None]":
          
          return self.protocol.write_message(message, binary=binary)
docs: Sends a message to the WebSocket server.
  
          If the stream is closed, raises `WebSocketClosedError`.
          Returns a `.Future` which can be used for flow control.
  
          .. versionchanged:: 5.0
             Exception raised on a closed stream changed from `.StreamClosedError`
             to `WebSocketClosedError`.