Macro rstat::params

macro_rules! params {
    (@munch () -> {$(#[$attr:meta])* $name:ident $(($id:ident: $ty:ident<$($ity:ident),*>))*}) => { ... };
    (@munch ($id:ident: $ty:ident<$($ity:ident),*>) -> {$($output:tt)*}) => { ... };
    (@munch ($id:ident: $ty:ident<$($ity:ident),*>, $($next:tt)*) -> {$($output:tt)*}) => { ... };
    ($(#[$attr:meta])* $name:ident { $($input:tt)*} ) => { ... };
}