How can I find all the possible combinations of a list of lists (in Python)?
<p>I have the following structure in Python:</p>

<pre><code>letters = [['a', 'b', 'c'], ['p', 'q', 'r', 's'], ['j', 'k', 'l']]
</code></pre>

<p>I would like to find all the possible combinations of letters in the order that they currently exist. For the example above this would be:</p>

<pre><code>apj
apk
apl
aqj
aqk
aql
...
csk
csl
</code></pre>

<p>This seems like it should be a very simple thing to do but I cannot figure it out.</p>
