public static int GetHashCode <A>(A x, A y) => HashableClass <A> .GetHashCode(x);
public int GetHashCode(A x) => HashableClass <A> .GetHashCode(x);
public static int GetHashCode <A>(A x, A y) => HashableClass <A> .GetHashCode(x);
public int GetHashCode(A x) => HashableClass <A> .GetHashCode(x);