# File lib/classifier/lsi.rb, line 61
    def add_item( item, *categories, &block )
      clean_word_hash = block ? block.call(item).clean_word_hash : item.to_s.clean_word_hash
      @items[item] = ContentNode.new(clean_word_hash, *categories)
      @version += 1
      build_index if @auto_rebuild
    end