+ SCM p1 = left_ev->get_property ("pitch");
+ SCM p2 = right_ev->get_property ("pitch");
+ if ((enharmonic
+ ? (unsmob<Pitch> (p1) && unsmob<Pitch> (p2) &&
+ unsmob<Pitch> (p1)->tone_pitch () == unsmob<Pitch> (p2)->tone_pitch ())
+ : ly_is_equal (p1, p2))