Macro count_tts

macro_rules! count_tts {
    () => { ... };
    ($one:tt) => { ... };
    ($($a:tt $b:tt)+) => { ... };
    ($odd:tt $($a:tt $b:tt)+) => { ... };
}

macro_rules! implementation of count_tts. Source: https://github.com/camsteffen/count-tts