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run code in 500+ PHP versions simultaneously
<?php $array = [false, false, false]; $key = 0; // $array[$key++] ||= true; $array[$key] = $array[$key] || true; ++$key; // $array[++$key] ||= true; ++$key; $array[$key] = $array[$key] || true; assert($array === [true, false, true]); var_dump($array);

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