public function removeFromList()
    {
        // Keep the list modification query for the save() transaction
        $this->sortableQueries[] = array(
            'callable'  => array('\CustomerGroup\Model\CustomerGroupQuery', 'sortableShiftRank'),
            'arguments' => array(-1, $this->getPosition() + 1, null)
        );
        // remove the object from the list
        $this->setPosition(null);


        return $this;
    }