Why do `prev = poss[0]` and `prev = 0` behave differently?
<p>I have a question about this code:</p>

<pre><code>    poss = [6,9,20]

for n in range(6,66):
    if(n%6) == 0 or (n%9) == 0 or (n%20) == 0:
        poss.append(n)
poss.sort()
count = 0
prev = poss[0] 

for p in poss:
    print p
    if prev == p:
        del poss[count]
    count += 1
    prev = p

print poss
</code></pre>

<p>The 2nd for loop is intended to get rid of duplicates in the poss list and this code works correctly.  However, if I change the line:</p>

<pre><code>prev = poss[0]
</code></pre>

<p>to</p>

<pre><code>prev = 0
</code></pre>

<p>it won't correctly delete them.  For the life of me, I can't figure out why.</p>
