new_contents: # Copyright 2018 Google Inc.
  #
  # 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.
  
  def groupto(it, l):
      res = []
      for i in it:
          res.append(i)
          if len(res) == l:
              yield res
              res = []
      if res:
          yield res
  
  def dumphex(b):
      for i, l in enumerate(groupto(b, 16)):
          print(f"{i*16:8x} {' '.join(f'{e:02x}' for e in l)}")
  
subject: Add dumphex.py, useful for debugging