TypeError: unhashable type: 'list', Remove duplicate items in a list
<p>When I type the following code. I just try to remove the duplicate items in an list. There may be 10K pairs in this list.</p>

<pre><code>&gt;&gt;&gt; t = [['a','1'],['a','1'],['a','2']...]
&gt;&gt;&gt; t = list(set(t))

Traceback (most recent call last):
File "&lt;pyshell#19&gt;", line 1, in &lt;module&gt;
t = list(set(t))
TypeError: unhashable type: 'list'
&gt;&gt;&gt;
</code></pre>
