n = pa[k - 1]->rb_link[da[k - 1]] =
  tree->rb_alloc->libavl_malloc (tree->rb_alloc, sizeof *n);
if (n == NULL)
  return NULL;

n->rb_data = item;
n->rb_link[0] = n->rb_link[1] = NULL;
n->rb_color = RB_RED;
tree->rb_count++;
tree->rb_generation++;