code: function nextWorker(cb) {
      seneca.act('role:loadbalance,hook:balance', {
        workers: workers,
        lastWorker: lastWorker
      }, function (err, worker) {
        if (!worker) return cb(new Error('No up backend found'))
        lastWorker = worker
        cb(null, worker)
      })
    }
docs: Get the next worker by asking the `balance` hook for one. Default one is round robin, as implemented in `roundRobin`.