Write some code, that will flatten an array of arbitrarily nested arrays of integers into a flat array of integers. e.g. [[1,2,[3]],4] -> [1,2,3,4].

Flatten.php

class Flatten {
    /*
    * Flatten an array
    *
    * @param array $a_data Array unflatten
    * @return array
    */
    public static function array_flatten($array_data){
        if (empty($array_data))
            return array();
        $it = new RecursiveIteratorIterator(new RecursiveArrayIterator($array_data));
        foreach ($it as $value) {
            $result[]=$value;
        }
        return $result;
    }
    /*
    * Flatten an json array
    *
    * @param json $json_data Json array unflatten
    * @return json
    */
    public static function json_flatten($json_data){
        return json_encode(self::array_flatten(json_decode($json_data)));
    }
}

//Input [[1,2,[3]],4]
$input="[[1,2,[3]],4]";
//Output [1,2,3,4]
echo Flatten::json_flatten($input);
?>