public function getAverageByCategory(Collection $answers, Collection $categories): Collection 	{ 		$categories_collection = collect();  		foreach ($categories as $category) { 			$answer_score = $answers->whereIn('question_id', $category->questions->pluck('id')->all())->avg('answer_value'); 			$categories_collection->push(collect([ 				'id' => $category->id, 				'value' => $answer_score, 			])); 		}  		return $categories_collection; 	}