code: def test_momentum(self):
      x_train, x_test, y_train, y_test = simple_classification()
      optimizer = algorithms.Momentum(
          self.network,
          step=0.35,
          momentum=0.99,
          batch_size=None,
          verbose=False,
          nesterov=True,
      )
  
      optimizer.train(x_train, y_train, x_test, y_test, epochs=30)
      self.assertGreater(0.15, optimizer.errors.valid[-1])
  
file_path: neupy/tests/algorithms/gd/test_optimizers.py
imports: from functools import partial
  from neupy import algorithms, layers
  from helpers import simple_classification, compare_networks
  from base import BaseTestCase
label_desc: Use image node_id 6 for calling the OptimizersTestCase obj's underlying member method code with example usage: obj.test_momentum() without return types