message: Update error messages to reference post TF 1.7 symbol for `Input`.
diff: @@ -197,7 +197,7 @@ class Network(base_layer.Layer):
  if not hasattr(x, '_keras_history'):
  cls_name = self.__class__.__name__
  raise ValueError('Input tensors to a ' + cls_name + ' ' +
  - 'must come from `tf.layers.Input`. '
  + 'must come from `tf.keras.Input`. '
  'Received: ' + str(x) +
  ' (missing previous layer metadata).')
  # Check that x is an input tensor.
  @@ -207,14 +207,14 @@ class Network(base_layer.Layer):
  layer._inbound_nodes and layer._inbound_nodes[0].inbound_layers):
  cls_name = self.__class__.__name__
  logging.warning(cls_name + ' inputs must come from '
  - '`tf.layers.Input` (thus holding past layer metadata), '
  + '`tf.keras.Input` (thus holding past layer metadata), '
  'they cannot be the output of '
  'a previous non-Input layer. '
  'Here, a tensor specified as '
  'input to "' + self.name + '" was not an Input tensor, '
  'it was generated by layer ' + layer.name + '.\n'
  'Note that input tensors are '
  - 'instantiated via `tensor = tf.layers.Input(shape)`.\n'
  + 'instantiated via `tensor = tf.keras.Input(shape)`.\n'
  'The tensor that caused the issue was: ' + str(x.name))
  for x in self.outputs:
  if not hasattr(x, '_keras_history'):
  