public function scopeByType(Builder $query, ?SurveyType $survey_type = null): Builder 	{ 		return $query->where(function (Builder $query) use ($survey_type) { 			$query->whereNull('survey_type')->when($survey_type, function ($query) use ($survey_type) { 				$query->orWhere('survey_type', $survey_type->value); 			}); 		}); 	}