code: def _get_slots(self, empty_uid=False):
          
          slots = list()
          for uid, position in self.uids_strpositions.items():
              if empty_uid and not uid.startswith("empty-"):
                  continue
              elif not empty_uid and uid.startswith("empty-"):
                  continue
              tokens = position.split(":")
              slots.append(to_int(tokens[0]))
          return sorted(list(set(slots)))
docs: Returns a list with the position number of the slots that are
          occupied (if empty_uid=False) or are empty (if empty_uid=True)
  
          :param empty_uid: True exclude occupied slots. False excludes empties
          :return: sorted list with slot numbers