fret_board_ = make_item ("FretBoard", note_events_[0]->self_scm ());
SCM fret_notes = ly_cxx_vector_to_list (note_events_);
SCM proc = get_property ("noteToFretFunction");
if (ly_is_procedure (proc))
fret_board_ = make_item ("FretBoard", note_events_[0]->self_scm ());
SCM fret_notes = ly_cxx_vector_to_list (note_events_);
SCM proc = get_property ("noteToFretFunction");
if (ly_is_procedure (proc))