title: Pymongo bulk inserts
body: <p>I am trying to insert documents in bulk. But it doesn't insert more than 84 documents during bulk insert. 
  Gives me this error: </p>
  
  <pre><code>in insert pymongo.errors.InvalidOperation: cannot do an empty bulk insert
  </code></pre>
  
  <p>Is it possible to do batch inserts, like inserting 50 documents per insert?</p>