public function save($callback)
    {
        foreach ($this as $object) {
            call_user_func($callback, $object);
            if($object->changes()) $object->save();
        }

        return $this;
    }
public function save($callback)
    {
        foreach ($this as $object) {
            call_user_func($callback, $object);
            if($object->changes()) $object->save();
        }

        return $this;
    }
public function save ( $ callback ) { foreach ( $ this as $ object ) { call_user_func ( $ callback , $ object ) ; if ( $ object -> changes ( ) ) $ object -> save ( ) ; } return $ this ; }
Applies a callback to all objects in Collection, saves them if
the object has changed
@chainable
Applies a callback to all objects in Collection saves them if the object has changed