code: def __str__(self):
      return "{}{}".format(self._device_type, self._index)
  
imports: import inspect
  import json
  import os
  import sys
  import types
  from collections import OrderedDict
  from enum import Enum
  from typing import Dict, List, Union
  from rl_coach.core_types import TrainingSteps, EnvironmentSteps, GradientClippingMethod, RunPhase, SelectedPhaseOnlyDumpFilter, MaxDumpFilter
  from rl_coach.filters.filter import NoInputFilter
  from rl_coach.logger import screen
label_desc: Use image node_id 4 for calling the Device obj's underlying member method code with example usage: obj.__str__() and returns: str