use {
    std::{
        collections::HashSet,
        iter::FromIterator,
    },
};

#[allow(unused)]
#[derive(PartialEq, Eq, Hash, Debug)]
enum E {
    A,
    B,
    C,
}

fn main() {
    let set = HashSet::<E>::from_iter(vec![E::A, E::B].into_iter());
    println!("{:?}", set);
}