new_contents: #!/usr/bin/env python3
  
  # Copyright 2018 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
  #
  #     https://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.
  
  ''' Combine file from:
    * script argument 1
    with content of file from:
    * script argument 2
    using the beginning of line separators
    hardcoded using regexes in this file:
  
    We exclude any text using the separate
    regex specified here
  '''
  
  import re
  import sys
  
  insert_separator_regex = '(.*?\[\^\]\:\ \(autogen_docs_start\))(.*?)(\n\[\^\]\:\ \(autogen_docs_end\).*?$)'
  exclude_separator_regex = '(.*?)Copyright 20\d\d Google LLC.*?limitations under the License.(.*?)$'
  
  if len(sys.argv) != 3:
    sys.exit(1)
  
  input = open(sys.argv[1], "r").read()
  replace_content = open(sys.argv[2], "r").read()
  
  # Exclude the specified content from the replacement content
  groups = re.match(exclude_separator_regex, replace_content, re.DOTALL).groups(0)
  replace_content = groups[0] + groups[1]
  
  # Find where to put the replacement content, overwrite the input file
  groups = re.match(insert_separator_regex, input, re.DOTALL).groups(0)
  output = groups[0] + replace_content + groups[2]
  open(sys.argv[1], "w").write(output)
  
subject: Add combine_docfiles.py helper