- var_dump: documentation ( source)
<?php
$a = null;
$a ??= true;
$a = [
['a' => true, 'b' => true],
['a' => false, 'b' => true],
['a' => true, 'b' => true],
['a' => false, 'b' => true]
];
$a = 1;
$a += 2 + 3;
$a = null;
var_dump((string) $a['test']['b']);