Methods sometimes need access to the Arc managing self. This is easy: fn f(self: Arc) (to own the reference count) or fn f(self: &Arc) (to borrow it with the possibility of owning a count later by clone()). The former has the issue that every method call consumes self so many calls need o.clone().f() which is very unergonomically and it's slower because of the forced atomic inc/dec. But the &Arc version works, so whatever. However, if I want to pass around an Arc, then...
