Macro hashset 

macro_rules! hashset {
    () => { ... };
    ($($key:expr,)+) => { ... };
    ($($key:expr),*) => { ... };
}

Generates the code to initialize a HashSet.

The macro can be followed by parentheses or square brackets.

Example

let days = hashset!["Monday", "Tuesday", "Wednesday"];
// => HashSet::from(["Monday", "Tuesday", "Wednesday", ])
assert_eq!(days, HashSet::from(["Monday", "Tuesday", "Wednesday"]));