Macro cmd 

macro_rules! cmd {
    ($name:ident; help:$help:expr; :$default:expr; $($fname:expr=> $($str:literal)|*),*$(,)?) => { ... };
    ($name:ident; help:$help:expr; .$cmd:ty; :$default:expr; $($fname:expr=> $($str:literal)|*),*$(,)?) => { ... };
    ($name:ident; help:$help:expr; $(.$cmd:ty;)? $($fname:expr=> $($str:literal)|*),*$(,)?) => { ... };
    (help:$help:expr; $(.$cmd:ty;)? $(:$default:expr;)? $($fname:expr=> $($str:literal)|*),*$(,)?) => { ... };
}