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run code in 300+ PHP versions simultaneously
<?php $a = array('a' => "test", 'b' => 'aa'); $a['a'] = array(); $a['a'] += array('bb' => "gdaf"); var_dump($a); ?>
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
array(2) { ["a"]=> array(1) { ["bb"]=> string(4) "gdaf" } ["b"]=> string(2) "aa" }

preferences:
309.67 ms | 405 KiB | 455 Q