+MAKE_SCHEME_CALLBACK (Lyric_combine_music, length_callback, 1);
+SCM
+Lyric_combine_music::length_callback (SCM m)
+{
+ Music *me = unsmob<Music> (m);
+ Music *melody = unsmob<Music> (scm_car (me->get_property ("elements")));
+ return melody->get_length ().smobbed_copy ();
+}