Function milestone_value 

pub fn milestone_value(title: &str) -> String

The value of the trailer Milestone: for the milestone title: the wave by its number, Wave N with no name, or the whole title of a milestone that is not a wave (01M518A07QF1YACBYT91M0DD1R).

assert_eq!(hygiene::milestone_value("Wave 28: cloud, fixes that slow the work"), "Wave 28");
assert_eq!(hygiene::milestone_value("Wave 3"), "Wave 3");
assert_eq!(hygiene::milestone_value("Backlog"), "Backlog");