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);
}