xi

    From(foo) |>
    Where(Get.value .< 10) |>
    Join(From(bar) |> As(:bar), on = Get.bar.id .== Get.bar_id) |>
    Where(Get.bar.other_value .> 20) |>
    Select(Get.group, Get.value) |>
    Group(Get.group) |>
    Where(Agg.sum(Get.value) .> 100) |>
    Order(Get.group)

    class cached_property(object):

        def __init__(self, fget):
            self.fget = fget
            self.__name__ = fget.__name__
            self.__module__ = fget.__module__
            self.__doc__ = fget.__doc__

        def __get__(self, obj, objtype=None):
            if obj is None:
                return self
            value = self.fget(obj)
            # For a non-data descriptor (`__set__` is not defined),
            # `__dict__` takes precedence.
            obj.__dict__[self.__name__] = value
            return value

    post(id integer, created timestamp)
    comment(id integer, post_id integer)