code: def _extract_error():
      
  
      error_num = errno()
  
      try:
          error_string = os.strerror(error_num)
      except (ValueError):
          return str_cls(error_num)
  
      if isinstance(error_string, str_cls):
          return error_string
  
      return _try_decode(error_string)
docs: Extracts the last OS error message into a python unicode string
  
      :return:
          A unicode string error message