code: def test_calc_gradient(differentiable_model):
      _calc_gradient(
          differentiable_model.output, [differentiable_model.input]
      )
  
imports: import pytest
  import keras.backend
  from keras.models import Sequential, Model
  from keras.layers import Dense, Activation, Conv2D, GlobalAveragePooling2D, Input, Lambda
  from keras.backend import epsilon
  import numpy
  from eli5.keras.explain_prediction import explain_prediction, _validate_doc, _get_activation_layer
  from eli5.keras.gradcam import _get_target_prediction, _calc_gradient, gradcam
label_desc: Use image node_id 10 for calling a global function with example usage: test_calc_gradient(differentiable_model) without return types