use std::collections::HashSet;
fn main() {
let mut hs = HashSet::new();
hs.insert("Rust");
hs.insert("C");
hs.insert("C");
hs.insert("C++");
hs.insert("Java");
if hs.contains(&"Rust") {
println!("found");
} else {
println!("not found");
}
}
/*
run:
found
*/