code: def test_make_digits_flip_mode(self):
      data, labels = datasets.load_digits()
      noisy_data, noisy_labels = datasets.make_digits(
          noise_level=0.5, n_samples=100, mode="flip"
      )
  
      diff_signs = np.sign(data[noisy_labels] - noisy_data).flatten()
      self.assertEqual({-1, 0, 1}, set(diff_signs))
  
file_path: neupy/tests/datasets/test_digits.py
imports: import numpy
  from neupy import datasets
  from base import BaseTestCase
label_desc: Use image node_id 4 for calling the DiscreteDigitsDatasetTestCase obj's underlying member method code with example usage: obj.test_make_digits_flip_mode() without return types