+
+LY_DEFINE (ly_grob_get_vertical_axis_group_index, "ly:grob-get-vertical-axis-group-index",
+ 1, 0, 0, (SCM grob),
+ "Get the index of the vertical axis group the grob @var{grob} belongs to;"
+ " return @code{-1} if none is found.")
+{
+ Grob *gr = unsmob_grob (grob);
+
+ LY_ASSERT_SMOB (Grob, grob, 1);
+
+ return scm_from_int (Grob::get_vertical_axis_group_index (gr));
+}