code: func FindSentencesFrom(ranks *Rank, id int, limit int) []Sentence {
  	var sentences []Sentence
  
  	limit = id + limit - 1
  
  	for i := id; i <= limit; i++ {
  		sentences = append(sentences, Sentence{i, ranks.SentenceMap[i]})
  	}
  
  	return sentences
  }
docs: // FindSentencesFrom function has wrapper textrank.FindSentencesFrom. Use the
  // wrapper instead.