code: def _add_baseline_to_exclude_files(args):
      
      baseline_name_regex = r'^{}$'.format(args.import_filename[0])
  
      if not args.exclude_files:
          args.exclude_files = baseline_name_regex
      elif baseline_name_regex not in args.exclude_files:
          args.exclude_files += r'|{}'.format(baseline_name_regex)
docs: Modifies args.exclude_files in-place.