How can I flatten lists without splitting strings?
<p>I'd like to flatten lists that may contain other lists <em>without</em> breaking strings apart. For example:</p>

<pre><code>In [39]: list( itertools.chain(*["cat", ["dog","bird"]]) )
Out[39]: ['c', 'a', 't', 'dog', 'bird']
</code></pre>

<p>and I would like</p>

<pre><code>['cat', 'dog', 'bird']
</code></pre>
