在Elm 0.18中如何在一个函数中触发多条消息？

import Html exposing (Html, button, div, text)
import Html.Events exposing (onClick)
import Platform.Cmd exposing (Cmd)


-- 消息类型
type Msg
    = ShowMessage String
    | ShowAnotherMessage String


-- 更新函数
update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        ShowMessage message ->
            ( model, Cmd.none )

        ShowAnotherMessage message ->
            ( model, Cmd.none )


-- 视图函数
view : Model -> Html Msg
view model =
    div []
        [ button [ onClick (ShowMessage "Hello!") ] [ text "Show Message" ]
        , button [ onClick (ShowAnotherMessage "Another message!") ] [ text "Show Another Message" ]
        ]


-- 主程序
main : Program Never Model Msg
main =
    Html.program
        { init = ( initialModel, Cmd.none )
        , update = update
        , view = view
        , subscriptions = \_ -> Sub.none
        }


-- 初始模型
initialModel : Model
initialModel =
    Model


-- 模型类型
type alias Model =
    {}


-- 运行程序
main =
    Html.programWithFlags
        { init = init
        , update = update
        , view = view
        , subscriptions = subscriptions
        }