code: func (j *Json) MustUint64(args ...uint64) uint64 {
  	var def uint64
  
  	switch len(args) {
  	case 0:
  	case 1:
  		def = args[0]
  	default:
  		log.Panicf("MustUint64() received too many arguments %d", len(args))
  	}
  
  	i, err := j.Uint64()
  	if err == nil {
  		return i
  	}
  
  	return def
  }
docs: // MustUInt64 guarantees the return of an `uint64` (with optional default)
  //
  // useful when you explicitly want an `uint64` in a single value return context:
  //     myFunc(js.Get("param1").MustUint64(), js.Get("optional_param").MustUint64(5150))