title: fastest way to python dict to json binary string
body: <p>I need to convert this python dict into binary json</p>
  
  <pre><code>   d = {'1': 'myval', '2': 'myval2'}
  
     json_binary_str = b'{"1": "myval", "2": "myval2"}'
  </code></pre>
  
  <p>in python 3, I have this :</p>
  
  <pre><code>   import ujson
     ujson.dumps(d)
  </code></pre>
  
  <p>but, this does not create binary string.
  How can I do this ?</p>