code: func FindSingleWords(ranks *Rank) []SingleWord {
  	var singleWords []SingleWord
  
  	for _, word := range ranks.Words {
  		singleWords = append(singleWords, SingleWord{
  			word.ID,
  			word.Token,
  			word.Weight,
  			word.Qty,
  		})
  	}
  
  	sort.Slice(singleWords, func(i, j int) bool {
  		return singleWords[i].Weight > singleWords[j].Weight
  	})
  
  	return singleWords
  }
docs: // FindSingleWords function has wrapper textrank.FindSingleWords. Use the
  // wrapper instead.