docs: def login(self, username=None, password=None):
          """Login to a vSphere server.
  
          >>> client.login(username='Administrator', password='strongpass')
  
          :param username: The username to authenticate as.
          :type username: str
          :param password: The password to authenticate with.
          :type password: str
          """
          if username is None:
              username = self.username
          if password is None:
              password = self.password
          logger.debug("Logging into server")
          self.sc.sessionManager.Login(userName=username, password=password)
          self._logged_in = True