public PenViewModel()
 {
     _Pen = new Pen("MY PEN");
     penManager.CreatePen(_Pen, databaseManager);
     _animals                = new List <Animal>();
     _animals                = _Pen.GetAnimals();
     UpdateCommand           = new PenUpdateCommand(this);
     RemoveAnimalCommand     = new RemoveAnimalCommand(this);
     RemoveAllAnimalsCommand = new RemoveAllAnimalsCommand(this);
     AddPigCommand           = new AddPigCommand(this);
     AddCowCommand           = new AddCowCommand(this);
     AddChickenCommand       = new AddChickenCommand(this);
 }