static bool shift_less (Grob *const &, Grob *const &);
static Direction dir (Grob *me);
static Grob *accidentals (Grob *me);
- static Grob *arpeggio (Grob *me);
static Slice head_positions_interval (Grob *me);
static Grob *first_head (Grob *me);
static Grob *get_rest (Grob *me);