Ionic.Zip.ZipFile.RemoveEntryForUpdate C# (CSharp) Method

        private void RemoveEntryForUpdate(string entryName)
        {
            if (String.IsNullOrEmpty(entryName))
                throw new ArgumentNullException("entryName");

            string directoryPathInArchive = null;
            if (entryName.IndexOf('\\') != -1)
            {
                directoryPathInArchive = Path.GetDirectoryName(entryName);
                entryName = Path.GetFileName(entryName);
            }
            var key = ZipEntry.NameInArchive(entryName, directoryPathInArchive);
            if (this[key] != null)
                this.RemoveEntry(key);
        }