public static CarWithIInvariant Park(this CarWithIInvariant source)
{
((Car)source).Parked = true;
return(source);
}
public static CarWithIInvariant DriveFast(this CarWithIInvariant source)
{
((Car)source).DriveFast();
return(source);
}
public static CarWithIInvariant DriveFar(this CarWithIInvariant source)
{
((Car)source).NeedFuel = true;
return(source);
}