+Property_unset_iterator::process (Moment mom)
+{
+ Context *o = get_outlet ();
+ Music *m = get_music ();
+
+ send_stream_event (o, "UnsetProperty", m->origin (),
+ ly_symbol2scm ("symbol"), m->get_property ("symbol"),
+ ly_symbol2scm ("once"), m->get_property ("once"));
+
+ Simple_music_iterator::process (mom);
+}
+
+bool
+check_grob (Music *mus, SCM sym)
+{
+ bool g = to_boolean (scm_object_property (sym, ly_symbol2scm ("is-grob?")));
+
+ if (!g)
+ mus->origin ()->warning (_f ("not a grob name, `%s'",
+ ly_symbol2string (sym)));
+
+ return g;
+}
+
+SCM
+get_property_path (Music *m)