static void test_covariance()
{
Stack <Bear> bears = new Stack <Bear>();
ZooCleaner.Wash(bears);
//Stack<Animal> animals = bears; // Compile-time error
Bear[] bears2 = new Bear[3];
Animal[] animals = bears2; // OK
animals[0] = new Camel(); // Runtime error
}
static void Main(string[] args)
{
Stack <Bear> bears = new Stack <Bear>();
ZooCleaner.Wash(bears);
}
static void zoo()
{
Stak <Beer> beers = new Stak <Beer>();
ZooCleaner.Wash(beers);
}
