code: def hello(self,details=None):
          
          self._welcome_queue = queue.Queue()
  
          if details is None:
              details = {}
          if self.authid:
              details.setdefault('authid', self.authid)
          details.setdefault('agent', u'swampyer-1.0')
          details.setdefault('authmethods', self.authmethods or [u'anonymous'])
          details.setdefault('roles', {
                                          'subscriber': {},
                                          'publisher': {},
                                          'caller': {},
                                          'callee': {},
                                      })
          self._state = STATE_AUTHENTICATING
          self.send_message(HELLO(
                                  realm = self.realm,
                                  details = details
                              ))
  
          # Wait till we get a welcome message
          try:
              message = self._welcome_queue.get(block=True,timeout=self.timeout)
          except Exception as ex:
              raise ExWelcomeTimeout("Timed out waiting for WELCOME response")
          if message == WAMP_ABORT:
              raise ExAbort("Received abort when trying to connect: {}".format(
                      message.details.get('message',
                        message.reason)))
          self.session_id = message.session_id
          self.peer = message
          self._state = STATE_CONNECTED
  
          # And hook register/subscribe to anything that's required
          self.handle_join(message)
docs: Say hello to the server and wait for the welcome
              message before proceeding