code: def _decode_config(conf_str):
      
      conf_str = conf_str.strip()
  
      # convert "tttff" -> [True, True, True, False, False]
      conf = map(
          lambda x: True if x.upper() == "T" else False,
          list(conf_str)
      )
  
      return dict(zip(settings._ALLOWED_MERGES, conf))
docs: Decode string to configuration dict.
  
      Only values defined in settings._ALLOWED_MERGES can be redefined.