What does a function with 2 values on the right side mean? (Model -> Html msg) : <p>I have encountered that in the guide:</p>

<pre><code>viewValidation : Model -&gt; Html msg
viewValidation model =
  let
    (color, message) =
      if model.password == model.passwordAgain then
        ("green", "OK")
      else
        ("red", "Passwords do not match!")
  in
    div [ style [("color", color)] ] [ text message ]
</code></pre>

<p>So this is a function, which takes the <code>Model</code>. 
<code>Html msg</code> usually looks to me like we are calling the function <code>Html</code> with the argument <code>msg</code>.</p>

<p><code>msg</code> doesn't seem to play any role in any other part of the <code>viewValidation</code> function, though. So what does it mean and what is it for in this case?</p>
