fn main() -> i32 {
    let n = -1;
    if is_three(add_four(n)) {
        20
    } else {
        30
    }
}

pub fn add_four(n: i32) -> i32 {
    n + 4
}

fn is_three(n: i32) -> bool {
    n == 3
}

fn add_four_float(n: f64) -> f64 {
    n + 4.0
}