code: func Int64ValueOrZero(r *http.Request, k string) int64 {
  	val, err := Int64ValueOrDefault(r, k, 0)
  	if err != nil {
  		return 0
  	}
  	return val
  }
docs: // Int64ValueOrZero parses a form value into an int64 type.
  // It returns 0 if the parsing fails.