python list vs. tuple for on-the-fly key iteration
<p>Say I have components that I need to iterate through, for example "From" and "To."  As a convenience, I can iterate through these strings, but I don't need them stored for any extended period since I only have to do this once.  Would it be better to use a list or tuple in this instance?</p>

<pre><code>info = {}
for type in ('from', 'to'):
   info[type] = fetch(type);
</code></pre>

<p>Note that the above will work exactly the same if the tuple were changed to a list; I'm wondering if there is some preference.</p>
