docs: void processSubFringe(
      GBSNode      p)
    {
                                     /* Depth of a balanced T-zero tree for   */
                                     /*  this tree's K factor                 */
      int t0_depth = _tree.tZeroDepth();
  
      /* Determine top-most node we must visit in the tree walk               */
      int ntop = 0;                  /* This is the index within the          */
                                     /*  NodeStack that represents the top    */
                                     /*  of the sub-tree.  We start by        */
                                     /*  assuming we have to walk the whole   */
                                     /*  tree.                                */
      int xChild = 0;                /* Assume current node has no children   */
      if (p.hasChild())
        xChild = 1;                  /* Allow for terminal child              */
      if (index() > t0_depth)        /* Have at least a whole t0 sub-tree     */
        ntop = index() - (t0_depth - xChild);
      innerProcessSubTree(p, NodeStack.VISIT_RIGHT, ntop);
    }