Macro yarnn::sequential_impl

macro_rules! sequential_impl {
    ($p:expr, $t:ty { $($name:ident : $val:expr),* }) => { ... };
    ($p:expr, $t:ty { $($name:ident : $val:expr),* }, $($tt:tt)*) => { ... };
    ($p:expr, $t:ty) => { ... };
    ($p:expr, $t:ty, $($tt:tt)*) => { ... };
}