# bag of parts

  # for each item
    # for each existing part
      # if this item's kbits intersect this part's kbits,
        # union up the keywords
        # for all other parts
          # if this part's kbits intersect that part's kbits,
            # merge that part into this part
    # prune parts emptied by merger
    # create a new part if no intersections found