How to indicate it's the last page in a paginate function? done isn't accessible

[tttp]

Hi,

I'm using a not very documented feature, hopefully it's meant to be a stable one: using a function on paginate:

function mypaginate(context,data) {
  // do things to find the params for the next page
  if (next_page) {
      return {page: 42,other_param:whatever...}
  } else { // how to tell there isn't a new page?
     // i want to make it done("no more pages")
     return "404_does_not_exists"; // this is a hack, that will happen to be returning an invalid url
  }
}

osmosis...
   .paginate(mypaginate)

in the "normal" pagination mode (with selector) it does call return done('no URL found in ' + selector), but the callback function isn't available from the pagination function

Could I PR a change so if the pagination function returns null or false, it means it will call done('no URL found') instead of trying to fetch the page no matter what?