public function demographicQuestionsPpi(?string $clientSurveyId = null, ?string $code = null): self 	{ 		return $this->state([ 			'class' => QuestionClass::PpiDemographic->value, 			'category_id' => null, 			'client_survey_id' => $clientSurveyId, 			'code' => $code, 		]); 	}