title: ensure_index with key_or_list
body: <p>I'm trying to install this software, a few scripts for searching in a local mongodb database:
  <a href="https://github.com/wimremes/cve-search/blob/master/README.md" rel="nofollow">https://github.com/wimremes/cve-search/blob/master/README.md</a></p>
  
  <p>Since the search.py script fail miserably, I'm trying to put some index as suggested:</p>
  
  <pre><code>db.cpe.ensureIndex( {id:1 } )
  db.cves.ensureIndex( {id:1} )
  db.cves.ensureIndex( {vulnerable_configuration:1} )
  db.vfeed.ensureIndex( {id:1} )
  </code></pre>
  
  <p>But this code is not working: ensureIndex fail with this error:</p>
  
  <pre><code>File "build/bdist.linux-i686/egg/pymongo/collection.py", line 1672, in __call__
  TypeError: 'Collection' object is not callable. If you meant to call the 'ensureIndex' method on a 'Collection' object it is failing because no such method exists.
  </code></pre>
  
  <p>and <code>ensure_index( {id:1})</code> return this:</p>
  
  <pre><code>TypeError: if no direction is specified, key_or_list must be an instance of list
  </code></pre>
  
  <p>What shoud I do for ceating new indexes?</p>