function add_odd_numbers($x, $y) {
assert('!(($x % 2) && ($y % 2))');
return ($x + $y);
}
$answer_one = add_odd_numbers(3, 5);
$answer_two = add_odd_numbers(2, 4);
echo "3 + 5 = $answer_one\n";
echo "2 + 4 = $answer_two\n";
?>