code: func Location(e error) (file string, line int) {
  	s := Stack(e)
  	if len(s) > 0 {
  		fnc, _ := runtime.CallersFrames(s[:1]).Next()
  		return fnc.File, fnc.Line
  	}
  	return "", 0
  }
docs: // Location returns zero values if e has no stacktrace