Ionic.Zip.ZipOutputStream.InsureUniqueEntry C# (CSharp) Method

        private void InsureUniqueEntry(ZipEntry ze1)
        {
            if (_entriesWritten.ContainsKey(ze1.FileName))
            {
                _exceptionPending = true;
                throw new ArgumentException(String.Format("The entry '{0}' already exists in the zip archive.", ze1.FileName));
            }
        }