code: def _test_preprocess(layer):
      a_out = layer.preprocess(A)
      assert a_out.shape == A.shape
  
file_path: spektral/tests/test_layers/convolutional/core.py
imports: import itertools
  import numpy
  import tensorflow
  from tensorflow.keras import Input, Model
  from spektral.utils.sparse import sp_matrix_to_sp_tensor
label_desc: Use image node_id 5 for calling a global function with example usage: _test_preprocess(layer) without return types