+ if (unisono_event_)
+ scm_gc_mark (unisono_event_->self_scm ());
+ if (mmrest_event_)
+ scm_gc_mark (mmrest_event_->self_scm ());
+ if (solo_one_event_)
+ scm_gc_mark (solo_one_event_->self_scm ());
+ if (solo_two_event_)
+ scm_gc_mark (solo_two_event_->self_scm ());