@Test
public void testJustArithmetic() {
Node<Integer,?> a = new IntegerNode(12);
Node<Integer,?> b = new IntegerNode(13);
Node<Integer,?> expr = new ArithmeticNode(Operator.plus, a, b);
assertEquals(25, expr.eval(null).intValue());
}
@SuppressWarnings("unchecked")
@Test
public void testJustRelation() {