code: func (j *Json) MustInt64(args ...int64) int64 {
  	var def int64
  
  	switch len(args) {
  	case 0:
  	case 1:
  		def = args[0]
  	default:
  		log.Panicf("MustInt64() received too many arguments %d", len(args))
  	}
  
  	i, err := j.Int64()
  	if err == nil {
  		return i
  	}
  
  	return def
  }
docs: // MustInt64 guarantees the return of an `int64` (with optional default)
  //
  // useful when you explicitly want an `int64` in a single value return context:
  //     myFunc(js.Get("param1").MustInt64(), js.Get("optional_param").MustInt64(5150))