private async void bn_downFile2_Click(object sender, EventArgs e)
        {
            string      BaseFTPpath     = tb_FTPpath2.Text;
            string      FTPusername     = tb_username2.Text;
            string      FTPpassword     = tb_password2.Text;
            string      FTPoutpath      = tb_filedownPath2.Text;
            string      fileRelatedInfo = tb_fileRelatedInfo.Text;
            FTPdownload ftp             = new FTPdownload(FTPusername, FTPpassword, BaseFTPpath);

            await FTPdownloadAllAsync(BaseFTPpath, FTPoutpath, fileRelatedInfo, FTPusername, FTPpassword, Pb_download);
        }
        Task FTPdownloadAllAsync(string baseFTPpath, string filePath, string related, string FTPusername, string FTPpassword, ProgressBar pb)
        {
            FTPdownload ftp = new FTPdownload(FTPusername, FTPpassword, baseFTPpath);

            return(Task.Run(() => ftp.DownloadAllRelated(baseFTPpath, filePath, related, pb)));
        }
 Task <bool> FTPdownloadAsync(string FTPURL, string filePath, string FTPusername, string FTPpassword, ProgressBar pb)
 {
     return(Task.Run(() =>
                     FTPdownload.Download(FTPURL, filePath, FTPusername, FTPpassword, pb)));
 }