FocusConvey is has the inverse effect of SkipConvey. If the top-level Convey is changed to `FocusConvey`, only nested scopes that are defined with FocusConvey will be run. The rest will be ignored completely. This is handy when debugging a large suite that runs a misbehaving function repeatedly as you can disable all but one of that function without swaths of `SkipConvey` calls, just a targeted chain of calls to FocusConvey.