docs: def order_by(self, *colnames):
          """
          orders the result set.
          ordering can only use clustering columns.
  
          Default order is ascending, prepend a '-' to the column name for descending
          """
          if len(colnames) == 0:
              clone = copy.deepcopy(self)
              clone._order = []
              return clone
  
          conditions = []
          for colname in colnames:
              conditions.append('"{}" {}'.format(*self._get_ordering_condition(colname)))
  
          clone = copy.deepcopy(self)
          clone._order.extend(conditions)
          return clone