@Override
    public boolean deleteChild(Expression<?> n) {
        if (!(n instanceof BinaryArithmeticOperator)) {
            return false;
        }
        if (children.get(0).equals(n))//left
        {
            children.set(0, ((Expression<?>) (n.randomChild())));
        } else if (children.get(1).equals(n))//right
        {
            children.set(1, ((Expression<?>) (n.randomChild())));
        } else {
            return false;
        }
        return true;
    }