The PHP declare keyword sets an execution directive for a block of code. If the declare statement is not followed by a block then the directive applies to the rest of the code in the file.

<?php
$count = 0;

function example() {
    global $count;
    $count++;
    echo $count . ' instructions executed<br>';
}

register_tick_function('example');

declare(ticks = 1) {
    $my_cars = ['Ferrari', 'Maserati', 'Alfa Romeo'];
    foreach($my_cars as $car) {
        echo $car . '<br>';
    }
}
?>