message: unused variable and add message
diff: @@ -796,7 +796,8 @@ class KerasCallbacksTest(keras_parameterized.TestCase):
  def test_RemoteMonitor(self):
  if requests is None:
  - return
  + self.skipTest('`requests` required to run this test')
  + return None
  monitor = keras.callbacks.RemoteMonitor()
  # This will raise a warning since the default address in unreachable:
  @@ -1171,6 +1172,7 @@ class KerasCallbacksTest(keras_parameterized.TestCase):
  def test_RemoteMonitorWithJsonPayload(self):
  if requests is None:
  self.skipTest('`requests` required to run this test')
  + return None
  with self.cached_session():
  (x_train, y_train), (x_test, y_test) = testing_utils.get_test_data(
  train_samples=TRAIN_SAMPLES,
  @@ -1239,8 +1241,7 @@ def list_summaries(logdir):
  ValueError: If an event file contains an summary of unexpected kind.
  """
  result = _SummaryFile()
  - for (dirpath, dirnames, filenames) in os.walk(logdir):
  - del dirnames # unused
  + for (dirpath, _, filenames) in os.walk(logdir):
  for filename in filenames:
  if not filename.startswith('events.out.'):
  continue
  @@ -1376,8 +1377,7 @@ class TestTensorBoardV2(keras_parameterized.TestCase):
  callbacks=[tb_cbk])
  events_file_run_basenames = set()
  - for (dirpath, dirnames, filenames) in os.walk(self.logdir):
  - del dirnames # unused
  + for (dirpath, _, filenames) in os.walk(self.logdir):
  if any(fn.startswith('events.out.') for fn in filenames):
  events_file_run_basenames.add(os.path.basename(dirpath))
  self.assertEqual(events_file_run_basenames, {'train'})
  