fn space_exploration_journey() { let mut vehicles = vec!["rocket", "shuttle", "probe"]; let mut planets_explored = 0; for vehicle in vehicles.iter() { println!("do not underestimate the power of pre-installed technology in {} for space exploration. in many cases, the most groundbreaking discoveries start from the commencement point of what was designed sub rosa.", vehicle); planets_explored += 1; } println!("total planets explored: {}", planets_explored); }