text: # Copyright 2016 The TensorFlow Authors. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  # ==============================================================================
  """Converts assert statements to their corresponding TF calls."""
  
  from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  import gast
  
  from tensorflow.python.autograph.core import converter
  from tensorflow.python.autograph.pyct import templates
  
  
  class AssertTransformer(converter.Base):
    """Transforms Assert nodes to Call so they can be handled as functions."""
  
    def visit_Assert(self, node):
      self.generic_visit(node)
  
      # Note: The lone tf.Assert call will be wrapped with control_dependencies
      # by side_effect_guards.
      template = """
        tf.Assert(test, (msg,))
      """
  
      if node.msg is None:
        return templates.replace(
            template, test=node.test, msg=gast.Str('Assertion error'))
      elif isinstance(node.msg, gast.Str):
        return templates.replace(template, test=node.test, msg=node.msg)
      else:
        raise NotImplementedError('can only convert string messages for now.')
  
  
  def transform(node, ctx):
    return AssertTransformer(ctx).visit(node)
  