refactor HeadlineIndex.parse
refactor HeadlineIndex.parse

kuad9/review_study,masawada/review,orangain/review,murashitas/review,masawada/review,krororo/review,krororo/review,kuad9/review_study,orangain/review,krororo/review,suzuki/review,kmuto/review,takahashim/review,kmuto/review,suzuki/review,murashitas/review,takahashim/review,kmuto/review