Macro libsugar::deque

macro_rules! deque {
    [] => { ... };
    [ $elem:expr; $n:expr ] => { ... };
    [ $($e:expr),* $(,)? ] => { ... };
}

new a VecDeque<T>

deque![a, b, c]

equivalent to

VecDeque::from(vec![a, b, c])