code: def having(self, expr):
          
          exprs = util.promote_list(expr)
          new_having = self._having + exprs
          return GroupedTableExpr(
              self.table,
              self.by,
              having=new_having,
              order_by=self._order_by,
              window=self._window,
          )
docs: Add a post-aggregation result filter (like the having argument in
          `aggregate`), for composability with the group_by API
  
          Parameters
          ----------
          expr : ibis.expr.types.Expr
  
          Returns
          -------
          grouped : GroupedTableExpr