protected function _addCondition($type, $fragment, $values = [])
        {
            $conditions_class_property_name = "_{$type}_conditions";

            if (!Arrays::is($values)) {
                $values = array($values);
            }

            array_push(
                $this->$conditions_class_property_name,
                array(
                    self::CONDITION_FRAGMENT => $fragment,
                    self::CONDITION_VALUES => $values,
                )
            );

            return $this;
        }