code: public void add(final String word, final V value)
  	{
  
  		char c = word.charAt(0);
  
  		LetterNode<V> node = get(c);
  		if (node == null) {
  			node = new LetterNode<V>(this.word + c);
  		}
  		this.nodes.put(c, node);
  
  		if (word.length() == 1) {
  			node.isKeyword = true;
  			node.value = value;
  			return;
  		}
  
  		node.add(word.substring(1), value);
  	}
docs: Adds a word and its related value.
  
  @param word
  keyword
  @param value
  related value