code: def get_instance(cls, device):
          
  
          if cls._nuis.get(device) is None:
              cls._nuis[device] = AndroidUiautomationPoco(device)
          return cls._nuis[device]
docs: This is only a slot to store and get already initialized poco instance rather than initializing again. You can
          simply pass the ``current device instance`` provided by ``airtest`` to get the AndroidUiautomationPoco instance.
          If no such AndroidUiautomationPoco instance, a new instance will be created and stored. 
  
          Args:
              device (:py:obj:`airtest.core.device.Device`): more details refer to ``airtest doc``
  
          Returns:
              poco instance