message: K-FAC: Deprecate tf.contrib.kfac.
  As LayerCollections are required to instantiate KfacOptimizer and FisherEstimator, a deprecation warning is printed upon instantiating LayerCollection.
diff: @@ -28,6 +28,7 @@ from collections import defaultdict
  from collections import OrderedDict
  from contextlib import contextmanager
  from functools import partial
  +import warnings
  import math
  import six
  @@ -171,6 +172,9 @@ class LayerCollection(object):
  def __init__(self,
  graph=None,
  name="LayerCollection"):
  + warnings.warn(
  + "tf.contrib.kfac is deprecated and will be removed by 2018-11-01. "
  + "Use https://pypi.python.org/pypi/kfac instead.")
  self.fisher_blocks = LayerParametersDict()
  self.fisher_factors = OrderedDict()
  self._linked_parameters = dict(
  