old_contents: #!/usr/bin/env python
  
  # 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.
  
  import os
  import sys
  
  from jinja2 import Environment, FileSystemLoader
  
  
  def main(argv):
      env = Environment(
          loader=FileSystemLoader('./autogen'),
      )
      template_options = {}
      templates = env.list_templates()
      for template_file in templates:
          template = env.get_template(template_file)
          rendered = template.render(template_options)
          with open(os.path.join("./", template_file), "w") as f:
              f.write(rendered)
  
  
  if __name__ == "__main__":
      main(sys.argv)
  
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.
  
  import os
  import sys
  
  from jinja2 import Environment, FileSystemLoader
  
  
  def main(argv):
      env = Environment(
          loader=FileSystemLoader('./autogen'),
      )
      template_options = {}
      templates = env.list_templates()
      for template_file in templates:
          template = env.get_template(template_file)
          rendered = template.render(template_options)
          with open(os.path.join("./", template_file), "w") as f:
              f.write(rendered)
  
  
  if __name__ == "__main__":
      main(sys.argv)
  
subject: Use python3 in generate_modules.py