/* Color of a red-black node. */
enum rb_color
  {
    RB_BLACK,   /* Black. */
    RB_RED      /* Red. */
  };

/* A red-black tree node. */
struct rb_node
  {
    struct rb_node *rb_link[2];   /* Subtrees. */
    void *rb_data;                /* Pointer to data. */
    unsigned char rb_color;       /* Color. */
  };

