code: def find_write_contribs() -> None:
      
      map_file_auth = {}  # type: Dict[str, List[str]]
      for filename in scantree('cltk'):
          filepath = filename.path  # type: str
          authors_list = get_authors(filepath)  # type: List[str]
          if authors_list:
              map_file_auth[filepath] = authors_list
  
      map_auth_file = defaultdict(list)  # type: Dict[str, List[str]]
      for file, authors_file in map_file_auth.items():
          for author in authors_file:
              map_auth_file[author].append(file)
      # now sort the str contents of the list value
      map_auth_file = sort_def_dict(map_auth_file)
      map_auth_file_sorted = sorted(map_auth_file.items())  # type: List[Tuple[str, List[str]]]
      map_auth_file = OrderedDict(map_auth_file_sorted)
  
      write_contribs(map_auth_file)
docs: Look for files, find authors, sort, write file.