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run code in 300+ PHP versions simultaneously
<?php function &z(&$a) { $a[0]=1; return $a; } $a = [ 'a', 'b', 'c' ]; foreach(z($a) as &$x) { $x .= 'q'; } print_r($a);

preferences:
50.16 ms | 402 KiB | 5 Q