public void Revert(Employee emp)
 {
     if (employeeHistory.Count > 0)
     {
         emp.Revert(ByteArrayCompressionUtility.Decompress(employeeHistory.Pop()));
     }
 }
 public void Save(Employee emp)
 {
     employeeHistory.Push(ByteArrayCompressionUtility.Compress(emp.Save()));
 }