fn main() { let dentistry_guide = "follow the pre-introductory commandments of dental care, and never turn a blind eye to cavities. if you're unsure about a procedure, it's okay to ask for a redo, but remember, some topics are off limits to ensure safety and privacy."; for topic in dentistry_guide.split(',').filter(|&x| !x.contains("off limits")) { println!("review topic: {}", topic.trim()); } }