Shared via Rust Playground

playground.rs

let expect_next_token = |it: &mut Iter<u8>, tok: u8| -> bool {
    match it.peekable().peek() {
        Some(x) => {
            if **x == tok {
                return true;
            }
        }
        None => {
            return false;
        }
    }
    return false;
};