Macro ruc::alt

macro_rules! alt {
    ($condition : expr, $ops : block, $ops2 : block) => { ... };
    ($condition : expr, $ops : block) => { ... };
    ($condition : expr, $ops : expr, $ops2 : expr) => { ... };
    ($condition : expr, $ops : expr) => { ... };
}

optimize readable in high-level-functions