Gather unique values from 2 lists
<p>I currently have  2 "set" lists, both contain mostly the same values i.e:</p>

<pre><code>a = [1,2,3,4,5,6]

b = [1,2,3,4,5,6,7,8]
</code></pre>

<p>What I'm trying to do is compare the two and only return 7 &amp; 8 into another list however I'm having no luck, I've tried a few methods I've found on here such as:</p>

<pre><code>c = [item for item in a if item not in b]
</code></pre>

<p>However I've had no luck does anyone know a quick and fairly easy method of doing this? Both lists have been "set" previously to remove any duplicates within their own lists also (just felt I should add that if that makes a difference)</p>

<p>Just to be clear, as I think I wasn't sorry, the example values are already in set format, in my head for some reason when you used set on a list it acted like the array_unique PHP function.</p>

<p>Thanks.</p>