code: func (s Int64) List() []int64 {
  	res := make(sortableSliceOfInt64, 0, len(s))
  	for key := range s {
  		res = append(res, key)
  	}
  	sort.Sort(res)
  	return []int64(res)
  }
docs: // List returns the contents as a sorted int64 slice.