Macro interleave::interleave

macro_rules! interleave {
    ($($e:expr),+,) => { ... };
    ($($e:expr),+) => { ... };
    () => { ... };
    ($t:ty;) => { ... };
    ($t:ty; $($e:expr),+,) => { ... };
    ($t:ty; $($e:expr),+) => { ... };
}

Main macro for creating a MultiIter