static void set_ordered (Grob *);
static Axis axis (Grob *);
static void add_element (Grob *, Grob *);
static int get_count (Grob *, Grob *);
static bool has_interface (Grob *);
static void set_ordered (Grob *);
static Axis axis (Grob *);
static void add_element (Grob *, Grob *);
static int get_count (Grob *, Grob *);
static bool has_interface (Grob *);