Macro lazy

macro_rules! lazy {
    ($(#[$attr:meta])* $vis:vis static ref $N:ident : $T:ty = $e:expr; $($rest:tt)*) => { ... };
    (@single, $(#[$attr:meta])* $vis:vis static ref $N:ident : $T:ty = $e:expr) => { ... };
    () => { ... };
}