code: def __getitem__(self, index: int) -> int:
      assert index < self._length
      return index
  
imports: from typing import Tuple
  import numpy
  import pytest
  from tensorflow.keras.utils import Sequence
  import determined
  from determined import keras
  from determined.common import check
  from tests.experiment import tf_utils
label_desc: Use image node_id 3 for calling the IdentitySequence obj's underlying member method code with example usage: obj.__getitem__(index) and returns: index