extern crate regex;

use regex::Regex;
use std::borrow::Cow;


fn main() {
    let out = do_regex("hello foo");
    println!("{}", out);
}

fn do_regex<'a>(txt: &'a str) -> Cow<str> {
    let rx = Regex::new("foo").unwrap();
    let out = rx.replace_all(txt, "bar");
    out
}