code: def _send_register_payload(self, websocket):
          
          file = os.path.join(os.path.dirname(__file__), HANDSHAKE_FILE_NAME)
  
          data = codecs.open(file, 'r', 'utf-8')
          raw_handshake = data.read()
  
          handshake = json.loads(raw_handshake)
          handshake['payload']['client-key'] = self.client_key
  
          yield from websocket.send(json.dumps(handshake))
          raw_response = yield from websocket.recv()
          response = json.loads(raw_response)
  
          if response['type'] == 'response' and \
                          response['payload']['pairingType'] == 'PROMPT':
              raw_response = yield from websocket.recv()
              response = json.loads(raw_response)
              if response['type'] == 'registered':
                  self.client_key = response['payload']['client-key']
                  self.save_key_file()
docs: Send the register payload.