Macro ht_set_sync 

macro_rules! ht_set_sync {
    ($($e:expr),*) => { ... };
}

Creates a HashTrieSet that implements Sync, containing the given arguments:

let s = HashTrieSet::new_sync()
    .insert(1)
    .insert(2)
    .insert(3);

assert_eq!(ht_set_sync![1, 2, 3], s);