"for item in list" - where does the None item come from?
<p>i got this list of objects with one item in it.</p>

<pre><code>    print self.parameters
    print len(self.parameters)
    for p in self.parameters:
        print p
</code></pre>

<p>when i print out the list and len of the lsit i see the expected: one item.
But when looping over the lsit i also get a None item...!?</p>

<pre><code>[&lt;__main__.Parameter object at 0x00000000022D4828&gt;]
1
&lt;__main__.Parameter object at 0x00000000022D4828&gt;
None
</code></pre>

<p>what is going on here?
(yes im sure, that the "None" output is from this print statement)</p>

<hr>

<p>EDIT:
i was manipulating the list i was looping over:</p>

<pre><code>print self.parameters
print len(self.parameters)
for p in self.parameters:
    print p
    (...)
    self.parameters.append(&lt;something that returned None&gt;)
</code></pre>
