code: private int getSupport(int[] itemset, int index, Node node) {
          int item = order[itemset[index]];
          Node child = node.children[item];
          if (child != null) {
              // If the index is 0, then this is the last element (i.e the
              // input is a 1 itemset)  and therefore item set found
              if (index == 0) {
                  return child.support;
              } else {
                  if (child.children != null) {
                      return getSupport(itemset, index - 1, child);
                  }
              }
          }
  
          return 0;
      }
docs: Returns the support value for the given item set if found in the T-tree
  and 0 otherwise.
  @param itemset the given item set.
  @param index the current index in the given item set.
  @param nodes the nodes of the current T-tree level.
  @return the support value (0 if not found)