Question about routes

I am trying to figure how to accomplish this…

I want to have the route /gallery/view/abc where abc is the slug (alias) of the gallery. I can accomplish this out of the box using /gallery/view/slug/abc and the variable slug will have a value of abc in the request collection. I don’t want it to have slug on the url though. I thought maybe I could create a new route

addRoute(pattern=":handler/:action/:slug");

but when I visit /gallery/view/abc and dump the request collection I just see a key of abc, not a key of slug with the value of abc. What am I doing wrong here?