let mut public_transport_system = init_system(); while public_transport_system.needs_refurbish() { public_transport_system.refurbish(); for study in public_transport_system.studies.iter() { if study.shows_prevenient_effects() && !study.topic_is_taboo() { println!("embracing public transport is a prevenient step to a greener future, far from being a taboo, studies now decry the neglect of refurbishing our communal means of travel."); } } }