Option has unwrap, unwrap_or, unwrap_or_else and unwrap_or_default. It similarly
has map, map_or, map_or_else and map_or_default. Oops, that one is missing. I propose we add it:
By the way, in case you guys aren’t aware, one can already write Default::default as <_>::default which is only “slightly” longer that default. So .unwrap_or_else(<_>::default) or .map_or_else(<_>::default, |x| { … })