/**
* Reduce, or fold, a collection down to a single value
*
* Overriden to load any data that has not yet been loaded.
*
* @param callback $filter The filter to apply.
* @param mixed $initial Initial value
* @return mixed A single reduced value
*/
public function reduce($filter, $initial = false)
{
$this->offsetGet(null);
return parent::reduce($filter, $initial);
}