title: NotImplementedError while using codecs.StreamWriter?
body: <p>While trying to download a mp3 from a Google Translate text to speech API I ran into an error while trying to use codesc. The code is below and the line returning the error is codecs.StreamWriter().</p>
  
  <pre><code>import requests, codecs
  
  def say(text):
  
      response = requests.get('http://translate.google.com/translate_tts?ie=UTF-8&amp;tl=en_us&amp;q='+text)
      print(response)
  
  
      print('Downloading %s...' % (text))
      with codecs.StreamWriter(codecs.open('output.mp3', 'wb','utf-8')) as fo:
          for chunk in response.iter_content(4096):
              fo.write(chunk)
  say("Jen hates sharks. Not really.")
  </code></pre>