code: def test_adam(self):
      x_train, x_test, y_train, y_test = simple_classification()
      optimizer = algorithms.Adam(
          self.network,
          step=0.1,
          verbose=False,
          epsilon=1e-4,
          beta1=0.9,
          beta2=0.99,
      )
      optimizer.train(x_train, y_train, x_test, y_test, epochs=200)
      self.assertGreater(0.2, 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 4 for calling the OptimizersTestCase obj's underlying member method code with example usage: obj.test_adam() without return types