[Rust] set demo

// Call HashSet from library
use std::collections::HashSet;

fn main() {
    // Create an empty set
    let mut set = HashSet::new();

    // Insert item into the set
    set.insert("C++");
    set.insert("Java");
    set.insert("Python");
    set.insert("Rust");
    set.insert("Go");

    // Check the property of the set
    assert_eq!(set.len(), 5);
    assert_eq!(set.contains("Rust"), true);
    assert_eq!(set.contains("Lisp"), false);

    // Remove item from the set
    set.remove("Python");

    // Check the property of the set
    assert_eq!(set.len(), 4);
    assert_eq!(set.contains("Rust"), true);
    assert_eq!(set.contains("Python"), false);
}