code: public int createIndex(String tokenForm) {
  		int[] index = (int[]) tokenForm2index.get(tokenForm);
  		if (index == null) {
  			index = new int[] { nextAttributeID };
  			tokenForm2index.put(tokenForm, index);
  			nextAttributeID++;
  		}
  		// add information about number of documents
  		// for the term
  		Integer integ = Integer.valueOf(index[0]);
  		int[] docfreq = (int[]) this.index2docfreq.get(integ);
  		if (docfreq == null) {
  			docfreq = new int[] { 0 };
  			index2docfreq.put(integ, docfreq);
  		}
  		docfreq[0]++;
  		return index[0];
  	}
docs: called from Document