How do I have a subrouter in Oak?

I want to use a subrouter in oak to handle part of the routing, how would I do that in Oak? here is an example in Express.js

app.use("/path/to/subrouter", subrouter);

app.use("/path/to/subrouter", subrouter);

app.use("/path/to/subrouter", subrouter);

app.use("/path/to/subrouter", subrouter);