function &array_get($arr_def, &$res_array, $default_value = '')
 {
     if ($size = sizeof($arr_def)) {
         $key = array_shift($arr_def);
         if (is_array($res_array) && isset($res_array[$key])) {
             if ($size > 1) {
                 return complex_array::array_get($arr_def, $res_array[$key]);
             } elseif ($size == 1) {
                 return $res_array[$key];
             }
         }
     }
     return $default_value;
 }