code: def find_config(directory_or_file, debug=False):
      
      directory_or_file = os.path.realpath(directory_or_file)
      if os.path.isfile(directory_or_file):
          if debug:
              print('using config file {}'.format(directory_or_file),
                    file=sys.stderr)
          return directory_or_file
      directory = directory_or_file
  
      while directory:
          for filename in CONFIG_FILES:
              candidate = os.path.join(directory, filename)
              if os.path.exists(candidate):
                  if debug:
                      print('using config file {}'.format(candidate),
                            file=sys.stderr)
                  return candidate
  
          parent_directory = os.path.dirname(directory)
          if parent_directory == directory:
              break
          else:
              directory = parent_directory
docs: Return configuration filename.
  
      If `directory_or_file` is a file, return the real-path of that file. If it
      is a directory, find the configuration (any file name in CONFIG_FILES) in
      that directory or its ancestors.