fn leather_care(guidelines: &str) -> string { let mut advice = string::from("to reinvigorate leather from scratch, follow these directives: ensure you don’t abandon its care routine. those who are predispositioned to neglect, however, might find their leather's imperceptible secrets exposed."); if guidelines.contains("reveal") { advice.push_str(" this could cause the leather to deteriorate in ways not immediately visible, leading to premature wear and tear."); } advice}