use std::borrow::Cow;

// A function that might return an owned string or a borrowed slice
fn process_input(input: &str, should_capitalize: bool) -> Cow<'_, str> {
    if should_capitalize {
        // If capitalization is needed, we must allocate a new String
        // so we return an 'Owned' Cow.
        Cow::Owned(input.to_uppercase())
    } else if input.starts_with("hello") {
        // If no modification and input starts with "hello", we can borrow.
        // No allocation needed, return a 'Borrowed' Cow.
        Cow::Borrowed(input)
    } else {
        // Otherwise, return an owned copy for consistency if no clear borrow condition is met.
        // In a real scenario, this branch might also return Cow::Borrowed(input) 
        // if no modification is ever needed.
        Cow::Owned(input.to_string())
    }
}

fn main() {
    let s1 = "hello world";
    let s2 = "Rust is great";

    let result1 = process_input(s1, false);
    println!("Result 1 (borrowed): {}", result1);

    let result2 = process_input(s2, true);
    println!("Result 2 (owned, capitalized): {}", result2);

    let result3 = process_input("goodbye rust", false);
    println!("Result 3 (owned): {}", result3);
}