<?php
function yieldTest()
{
$foo = 0;
echo yield -1;
// interpreted in PHP 5.x as
// echo (yield) - 1;
// interpreted in PHP 7 as
// echo yield (-1);
yield $foo or die;
// interpreted in PHP 5.x as
// yield ($foo or die);
// interpreted in PHP 7 as
// (yield $foo) or die;
}
foreach (yieldTest() as $item) echo $item;
-10