1234567891011121314151617open!Coretypepacked=T:Runner.t->packedlet(most_recent_driver:packedoptionref)=refNoneletregister_driverdriver=most_recent_driver:=Some(Tdriver)letinvalidate_observers=Core_bench_js.Test.create_with_initialization~name:"cleaning up observers..."(fun`init->(match!most_recent_driverwith|None->()|Some(Tdriver)->Runner.invalidate_observersdriver);most_recent_driver:=None;fun()->());;