code: def _lint():
      
      # Flake8 doesn't have an easy way to run checks using a Python function, so
      # just fork off another process to do it.
  
      # Python 3 compat:
      # - The result of subprocess call outputs are byte strings, meaning we need
      #   to pass a byte string to endswith.
      project_python_files = [filename for filename in get_project_files()
                              if filename.endswith(b'.py')]
      retcode = subprocess.call(
          ['flake8', '--max-complexity=10'] + project_python_files)
      if retcode == 0:
          print_success_message('No style errors')
      return retcode
docs: Run lint and return an exit code.