Macro array 

macro_rules! array {
    () => { ... };
    ($($x:expr),+ $(,)?) => { ... };
}

Construct a CBOR array from a list of expressions.

Each element is converted into a Value.

let empty = array![];
assert_eq!(empty.len(), Some(0));

let v = array![1, "hello", true];
assert!(v.data_type().is_array());