code: def set_identity(
      parent_layer: nn.Layer, layer_name: str, layer_index: str = None
  ) -> bool:
      """set the layer specified by layer_name and layer_index to Indentity.
  
      Args:
          parent_layer (nn.Layer): The parent layer of target layer specified by layer_name and layer_index.
          layer_name (str): The name of target layer to be set to Indentity.
          layer_index (str, optional): The index of target layer to be set to Indentity in parent_layer. Defaults to None.
  
      Returns:
          bool: True if successfully, False otherwise.
      """
  
      stop_after = False
      for sub_layer_name in parent_layer._sub_layers:
          if stop_after:
              parent_layer._sub_layers[sub_layer_name] = Identity()
              continue
          if sub_layer_name == layer_name:
              stop_after = True
  
      if layer_index and stop_after:
          stop_after = False
          for sub_layer_index in parent_layer._sub_layers[
              layer_name
          ]._sub_layers:
              if stop_after:
                  parent_layer._sub_layers[layer_name][
                      sub_layer_index
                  ] = Identity()
                  continue
              if layer_index == sub_layer_index:
                  stop_after = True
  
      return stop_after
  
imports: import math
  from typing import Any
  from typing import Callable
  from typing import Dict
  from typing import List
  from typing import Tuple
  from typing import Union
  import paddle
  import paddle.nn
  from paddle import concat
  from paddle import ParamAttr
  from paddle import reshape
  from paddle import split
  from paddle import transpose
  from paddle.nn import AdaptiveAvgPool2D
  from paddle.nn import BatchNorm
  from paddle.nn import Conv2D
  from paddle.nn import Dropout
  from paddle.nn import Linear
  from paddle.nn import MaxPool2D
  from paddle.nn.initializer import KaimingNormal
  from paddle.regularizer import L2Decay
label_desc: Use image node_id 2 for calling a global function with example usage: set_identity(parent_layer, layer_name, layer_index) and returns: stop_after