public GSM(string manufacturer, string model, int? price, string owner, Battery battery, Display display)
{
this.manufacturer = manufacturer;
this.model = model;
this.owner = owner;
this.price = price;
this.battery = new Battery("NA", 0f, 0f);
this.display = new Display();
}
public GSM(string manufacturer, string model, int price, string owner, Battery battery)
: this(manufacturer, model, price, owner, battery, new Display())
{
}