Weird behavior with var in dict
<pre><code>&gt;&gt;&gt; x = { 'a' : 'b' , 'c' : 'd' }

&gt;&gt;&gt;'a' and 'c' in x
True

&gt;&gt;&gt;'a' and 'b' in x
False

&gt;&gt;&gt;'b' and 'c' in x
True
</code></pre>

<p>If <code>in &lt;dict&gt;</code> checks for keys, how come the last one that looks up <code>b</code> returns <code>true</code> even if there is no such key <code>b</code>?</p>
