Edit requests of 普段は Union 型が返るけど、文字列で種類を渡したら具体的な型で返ってくる関数を作る

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We released Markdown parser changes on February 24, 2022. There may be some unexpected appearance changes in this update, because this article was posted before the changes.
Please don't forget to check the preview before updating your article.
For more information on the changes, please read this article.