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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)); $i++) array_walk(@array_filter($regions, function ($x) use ($i) { return $x & $i; }), function ($x, $region) use (&$list) { isset($list[$region]) and $list[$region] .= ","; $list[$region] .= $x; } ); var_dump($list);

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