code: def test_data_function():
      result = retrieve_data_string(test_data, verbose=False)
      assert "return X_train, Y_train, X_test, Y_test" not in result
      assert "def data():" not in result
      assert "nb_classes_return = 10" in result
      assert (
          "(X_train, y_train), (X_test, y_test) = mnist.load_data()"
          in result
      )
      assert (
          "Y_test = np_utils.to_categorical(y_test, nb_classes_return)"
          in result
      )
  
imports: from keras.datasets import mnist
  from keras.utils import np_utils
  from hyperas.optim import retrieve_data_string
label_desc: Use image node_id 2 for calling a global function with example usage: test_data_function() without return types