Macro mk_is_state_trait

macro_rules! mk_is_state_trait {
    ($lts:tt {$($finished:tt)*} {{$f0:ident, $($l:tt)*} $($f:tt)*} $($generic:tt)*) => { ... };
    ({$($glts:lifetime,)*} {$($finished:tt)*} {} $($generic:tt)*) => { ... };
}