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<?php $regions = [ 'int' => 1, 'nl' => 2, 'be' => 4, 'us' => 8, 'as' => 16, 'za' => 32, ]; for ($i = 0; $i < 1 << count($regions); $i++) array_walk($regions, function ($x, $region) use (&$list, $i) { if ($i & $x == 0) return; if (isset($list[$region])) $list[$region] .= ",$x"; else $list[$region] = $x; }); var_dump($list);

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