code: func (r *request) setQueryOptions(q *QueryOptions) {
  	if q == nil {
  		return
  	}
  	if q.Datacenter != "" {
  		r.params.Set("dc", q.Datacenter)
  	}
  	if q.AllowStale {
  		r.params.Set("stale", "")
  	}
  	if q.RequireConsistent {
  		r.params.Set("consistent", "")
  	}
  	if q.WaitIndex != 0 {
  		r.params.Set("index", strconv.FormatUint(q.WaitIndex, 10))
  	}
  	if q.WaitTime != 0 {
  		r.params.Set("wait", durToMsec(q.WaitTime))
  	}
  	if q.Token != "" {
  		r.params.Set("token", q.Token)
  	}
  }
docs: // setQueryOptions is used to annotate the request with
  // additional query options