if (!empty($this->must_implement) && !$this->_classesImplements($_cls, $this->must_implement, false, $logs)) {
                $logs[] = $this->_getErrorMessage(
                    count($this->must_implement)>1 ? 'Class "%s" must implement one of the following interfaces "%s"!' : 'Class "%s" must implement interface "%s"!',
                    $_cls, implode('", "', $this->must_implement));
                if ($flag & self::ERROR_ON_FAILURE) {