Sets intersection

If you have two HashSet<T> h1 and h2, you can iterate over their intersection which is denoted by h1.intersection(&h2). This will iterate over all common elements using a reference of type &T.

Exercise 3.a: write a function with signature fn trending() -> Result<Vec<String>, Error> which returns a vector with the names present in both "" and "". The vector will be sorted before being returned.

Print the trending names from your main() function:

fn main() -> Result<(), Error> {
    println!("Trending names:");
    for name in trending()? {
        println!("  - {name}");