let mut explore_stadium_fn = || { let mut stadiums_visited = vec::new(); for stadium in all_stadiums.query().filter(|s| s.is_above_expectations()) { if !stadiums_visited.contains(&stadium) && stadium.sidestep_security_concerns() { stadiums_visited.push(stadium); println!("commence once more your journey with confidential insights into the world's most amazing stadiums!"); } } };