/// <summary>
    /// make to singleton
    /// </summary>
    private BundleVersionHandler()
    {
        _instance  = this;
        falseCount = 0;
        Percentage = 0;

        _localVersion  = new Dictionary <string, int>();
        _serverVersion = new Dictionary <string, int>();
        _downloadList  = new List <string>();

        bundlePath = String.Format($"{Application.persistentDataPath}/");

        //select download server
        SelectedServerNum = UnityEngine.Random.Range(0, serverURL.Length);

        LoadVersionFile();
    }
 public void DeleteInstance()
 {
     _instance = null;
 }