python convert strings into sets of characters
<pre><code>c=['a,b,c','a,b,c','a,b']
for item in c:
    a=set(item.replace("'",""))
    b=list(a)
print b
</code></pre>

<p>It returns: </p>

<pre><code>['a','b',',']
</code></pre>

<p>What I want is : </p>

<pre><code>['a','b','c']
</code></pre>

<p>How do I convert these strings into sets of characters? </p>
