old_contents: # Copyright 2020 Google LLC
  #
  # 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.
  
  # Lint as: python3
  """Memoization decorator helper."""
  
  import functools
  
  _SENTINEL = object()
  
  
  def memoize(f):
    """Returns a version of the given callable that has memoized results."""
    cache = {}
  
    @functools.wraps(f)
    def memoizing_wrapper(*args):
      result = cache.get(args, _SENTINEL)
      if result is _SENTINEL:
        result = cache[args] = f(*args)
      return result
  
    return memoizing_wrapper
  
new_contents: # Lint as: python3
  #
  # Copyright 2020 Google LLC
  #
  # 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.
  
  """Memoization decorator helper."""
  
  import functools
  
  _SENTINEL = object()
  
  
  def memoize(f):
    """Returns a version of the given callable that has memoized results."""
    cache = {}
  
    @functools.wraps(f)
    def memoizing_wrapper(*args):
      result = cache.get(args, _SENTINEL)
      if result is _SENTINEL:
        result = cache[args] = f(*args)
      return result
  
    return memoizing_wrapper
  
subject: Tweak for memoize decorator.