/**
  * Convert collection items to select options hash array
  *
  * @return array
  */
 public function toOptionHash()
 {
     return parent::_toOptionHash('attribute_set_id', 'attribute_set_name');
 }
 /**
  * Retrieve option hash
  *
  * @return array
  */
 public function toOptionHash()
 {
     return parent::_toOptionHash('customer_group_id', 'customer_group_code');
 }