Intersection

To find the common elements of two sets, the intersection is a way of doing that. The definition also describes exactly that, which is why the naive implementation in Rust also follows that pattern, shown as follows:

pub fn intersection(self, other: TrieSet<K>) -> TrieSet<K> {
    let new = RefCell::new(TrieSet::new_empty());
    if self.length < other.length {
        self.walk(|k| {
            if other.contains(k) {
                new.borrow_mut().insert(k)
            }
        });
    } else {
        other.walk(|k| {
            if self.contains(k) {
                new.borrow_mut().insert(k)
            }
        });
    }
    new.into_inner()
}

As a last function, the difference is important, since it excludes common elements from the result set.