Macro function_group::function_group

macro_rules! function_group {
    (@Visibilty ($vis:vis fn $($tail:tt)*) -> (($($trait:tt)*), ($($func:tt)*))) => { ... };
    (@Visibilty (fn $($tail:tt)*) -> (($($trait:tt)*), ($($func:tt)*))) => { ... };
    (@Name (fn $name:ident $($tail:tt)*) -> (($($trait:tt)*), ($($func:tt)*))) => { ... };
    (@ReturnType ($name:ident -> $ret:ty {$($tail:tt)*}) -> (($($trait:tt)*), ($($func:tt)*))) => { ... };
    (@ReturnType ($name:ident {$($tail:tt)*}) -> (($($trait:tt)*), ($($func:tt)*))) => { ... };
    (@Define ($name:ident, $ret:ty, {$($tail:tt)*}) -> (($($trait:tt)*), ($($func:tt)*))) => { ... };
    (@Implementations ($name:ident, $ret:ty, $(($( $($var:ident)* : $type:ty),*) $code:block $(;)*)*)) => { ... };
    (@Implementations ($($tail:tt)*)) => { ... };
    ($($tail:tt)*) => { ... };
}