public override void Execute()
 {
     string name = ASkUser();
     if(name != null)
     {
         Document document = new Document();
         _application.Add(document);
         document.Open();
     }
 }
 public PasteCommand(Document doc)
 {
     _document = doc;
 }
 internal void Add(Document document)
 {
     throw new NotImplementedException();
 }