private static ZipArchive CreateZipArchive(string destFile, bool createNew)
        {
            AbstractFile zipFile = new DiskFile(destFile);

            if (createNew)
            {
                // In order to create a new zip file, all we have to do is make sure
                // that file does not exist before creating our ZipArchive.
                if (zipFile.Exists)
                {
                    zipFile.Delete();
                }
            }
            else
            {
                if (!zipFile.Exists)
                {
                    throw new ArgumentException(destFile + " is not exist!");
                }
            }

            return(CreateZipArchive(zipFile));
        }
        private static ZipArchive CreateZipArchive(string destFile, bool createNew)
        {
            AbstractFile zipFile = new DiskFile(destFile);

            if (createNew)
            {
                // In order to create a new zip file, all we have to do is make sure
                // that file does not exist before creating our ZipArchive.
                if (zipFile.Exists)
                {
                    zipFile.Delete();
                }
            }
            else
            {
                if (!zipFile.Exists)
                {
                    throw new ArgumentException(destFile + " is not exist!");
                }
            }

            return CreateZipArchive(zipFile);
        }