> example :: VoiceTwiml
> example =
>   response $ do
>     dial' (Left . dialNoun $ number "+15558675309" def) $ def
>              & callerId .~ Just "+15551112222"
>     end
>   where Twiml.Syntax{..} = def

>>> show example
<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Dial callerId="+15551112222">
    <Number>+15558675309</Number>
  </Dial>
</Response>