Macro define 

macro_rules! define {
    ($name:ident; help: $help:literal; flags {
        $($fname:ident: $ftype:ty = $($flag:literal)|* $(=> [$fnum:literal])?),*$(,)?
    }; args {
        $($aname:ident: $atype:ty $(=> [$num:literal])?),*$(,)? 
    };
    $(rest => $rname:ident: $rtype:ty;)?) => { ... };
}