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<?php $existing = ["president" => "trump"]; $new = ["president" => "anybody else"]; var_dump($existing + $new);
Output for 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 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
array(1) { ["president"]=> string(5) "trump" }

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139.21 ms | 407 KiB | 5 Q