static bool is_musical (Grob *);
static Moment when_mom (Grob *);
static bool is_used (Grob *);
static bool is_breakable (Grob *);
static bool is_musical (Grob *);
static Moment when_mom (Grob *);
static bool is_used (Grob *);
static bool is_breakable (Grob *);