Module() server functions don't return a value when invoked

[cpsievert]

For example, this should print "return value"

from typing import Callable
from shiny import *
from shiny.modules import *


def my_ui(ns: Callable[[str], str]) -> ui.Tag:
    return ui.input_action_button(ns("btn"), "Press")


def my_server(input: ModuleInputs, output: ModuleOutputs, session: ModuleSession):
    @reactive.Effect()
    def _():
        print(input.btn())

    return "return value"


my_module = Module(my_ui, my_server)

app_ui = ui.page_fluid(my_module.ui("foo"))


def server(input: Inputs, output: Outputs, session: Session):
    val = my_module.server("foo")
    print(val)


app = App(app_ui, server)