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run code in 300+ PHP versions simultaneously
<?php $array = array('a' => false, 'b' => null, 'c' => '', 'd' => 'd'); foreach ($array as $k => $v) { printf( '%s => %s isset = %s ake = %s', $k, $v, isset($array[ $k ]), array_key_exists($k, $array) ); }

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