Problem with Python's is None test?
<p>I like using the <em>is None</em> test for empty variables, it's very flexible, easy and useful.  It seems to have stopped working now:</p>

<pre><code>&gt;"" is None
False

&gt;[] is None
False

&gt;{} is None
False
</code></pre>

<p>What's going on?</p>

<p>I'm using Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40) [GCC 4.4.5], on Debian/Sid i686 GNU/Linux.</p>

<p>Edit: Awesome tip from Sven Marnach of using bool("").  brb, off to edit some code...</p>
