code: def fix_get_mnist_data():
      """
      Get the first 128 samples of the mnist test set with channels first format
  
      :return: First 128 sample/label pairs of the MNIST test dataset.
      """
      nb_test = 128
  
      (_, _), (x_test, y_test), _, _ = load_dataset("mnist")
      x_test = np.squeeze(x_test).astype(np.float32)
      x_test = np.expand_dims(x_test, axis=1)
      y_test = np.argmax(y_test, axis=1)
  
      x_test, y_test = x_test[:nb_test], y_test[:nb_test]
      return x_test, y_test
  
file_path: adversarial-robustness-toolbox/tests/estimators/certification/test_derandomized_smoothing.py
imports: import os
  import pytest
  import numpy
  from art.utils import load_dataset
  from art.estimators.certification.derandomized_smoothing import PyTorchDeRandomizedSmoothing, TensorFlowV2DeRandomizedSmoothing
  from tests.utils import ARTTestException
label_desc: Use image node_id 1 for calling a global function with example usage: fix_get_mnist_data() and returns: x_test,  y_test