> example :: VoiceTwiml
> example =
>   response $ do
>     say "Bom dia." $ def & voice .~ Just (Alice $ Just PtBR)
>                          & loop  .~ Just 2
>     end
>   where Twiml.Syntax{..} = def

>>> show example
<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Say voice="alice" loop="2" language="pt-BR">Bom dia.</Say>
</Response>