docs: def sub_location(self, nbr):
          """
          Return a given sub location, 0-based.
  
          Args:
              nbr:
  
          Returns:
          """
          assert nbr > -1, "Sub location number must be greater or equal to 0!"
          assert nbr < self.nbr_of_sub_locations() - 1, "Sub location number must be lower than %d!" % self.nbr_of_sub_locations() - 1
          return self._locations_list[nbr]