Python: List existing values in a list : <pre><code>data = [{u'class': u'A'}, {u'class': u'A'}, {u'class': u'B'}]
</code></pre>

<p>I want to get a list with all existing class values in data. Is there any efficient way to sort out double values?</p>

<pre><code>output = [{u'class': u'A'}, {u'class': u'B'}]
</code></pre>
