def send(self, data: Union[bytes, str], opcode: int = ABNF.OPCODE_TEXT) -> None:
        """
        send message

        Parameters
        ----------
        data: str
            Message to send. If you set opcode to OPCODE_TEXT,
            data must be utf-8 string or unicode.
        opcode: int
            Operation code of data. Default is OPCODE_TEXT.
        """

        if not self.sock or self.sock.send(data, opcode) == 0:
            raise WebSocketConnectionClosedException("Connection is already closed.")

        send message

        Parameters
        ----------
        data: str
            Message to send. If you set opcode to OPCODE_TEXT,
            data must be utf-8 string or unicode.
        opcode: int
            Operation code of data. Default is OPCODE_TEXT.
        
websocket/_app.py