rust-by-practice/solutions/crate-module/use-pub.md

use std::fmt::Result;
use std::io::Result as IoResult;

fn main() {}

use std::collections::*;

fn main() {
    let _c1:HashMap<&str, i32> = HashMap::new();
    let mut c2 = BTreeMap::new();
    c2.insert(1, "a");
    let _c3: HashSet<i32> = HashSet::new();
}

use std::collections::{HashMap, BTreeMap, HashSet};

fn main() {
    let _c1:HashMap<&str, i32> = HashMap::new();
    let mut c2 = BTreeMap::new();
    c2.insert(1, "a");
    let _c3: HashSet<i32> = HashSet::new();
}

// in lib.rs

// Add this line
pub use crate::front_of_house::hosting;