docs: def send(self, data, opcode=websocket.ABNF.OPCODE_TEXT):
          """
          Send message to server.
  
          data: message to send. If you set opcode to OPCODE_TEXT,
                data must be utf-8 string or unicode.
          opcode: operation code of data. default is OPCODE_TEXT.
          """
          self.ws_client.send(data, opcode)