Tie::set_interface (p); // cannot remove yet!
Tie::set_head (p, LEFT, prev_notes_[i]);
Tie::set_head (p, RIGHT, notes_[i]);
ties_.push (p);
Tie::set_interface (p); // cannot remove yet!
Tie::set_head (p, LEFT, prev_notes_[i]);
Tie::set_head (p, RIGHT, notes_[i]);
ties_.push (p);