code: def order_by(self, **kwargs):
          
          if kwargs:
              col, order = kwargs.popitem()
              self.order_clause = "order by {col} {order} ".format(
                  col=col, order=order)
          return self
docs: Analog to SQL "ORDER BY". +kwargs+ should only contain one item.
  
          examples)
  
          NO:  repo.order_by()
          NO:  repo.order_by(id="desc", name="asc")
  
          YES: repo.order_by(id="asc)