Sends a RTMMessage
        Should be called after starting the loop

        Args:
            message(RTMMessage): the sending message

        Raises:
            WebSocketConnectionClosedException: if the loop is closed

def send(self, message):
        """Sends a RTMMessage
        Should be called after starting the loop

        Args:
            message(RTMMessage): the sending message

        Raises:
            WebSocketConnectionClosedException: if the loop is closed
        """
        if "call_id" not in message:
            message["call_id"] = self.gen_call_id()

        self._ws.send(message.to_json())