code: public long learn(double confidence, PrintStream out) {
          long n = 0;
          ttree = fim.buildTotalSupportTree();
          for (int i = 0; i < ttree.root.children.length; i++) {
              if (ttree.root.children[i] != null) {
                  int[] itemset = {ttree.root.children[i].id};
                  n += learn(out, null, itemset, i, ttree.root.children[i], confidence);
              }
          }
          return n;
      }
docs: Mines the association rules. The discovered rules will be printed out
  to the provided stream.
  @param confidence the confidence threshold for association rules.
  @return the number of discovered association rules.