docs: def _user(self, user, real_name):
          """
          Sends the USER message.
          Required arguments:
          * user - Username to send.
          * real_name - Real name to send.
          """
          with self.lock:
              self.send('USER %s 0 * :%s' % (user, real_name))
              if self.readable():
                  self._recv()
                  self.stepback()