code: func (rank *Rank) AddNewWord(word string, prevWordIdx int, sentenceID int) (wordID int) {
  	wordID = len(rank.Words)
  	connectionLeft := make(map[int]int)
  
  	if prevWordIdx >= 0 {
  		connectionLeft[prevWordIdx] = 1
  	}
  
  	newWord := &Word{
  		ID:              wordID,
  		SentenceIDs:     []int{sentenceID},
  		ConnectionLeft:  connectionLeft,
  		ConnectionRight: make(map[int]int),
  		Token:           word,
  		Qty:             1,
  		Weight:          0,
  	}
  
  	rank.Words[wordID] = newWord
  	rank.WordValID[word] = wordID
  
  	return
  }
docs: // AddNewWord method adds a new word to the rank object and it defines its ID.