How do you check the presence of many keys in a Python dictinary?
<p>I have the following dictionary:</p>

<pre><code>sites = {
    'stackoverflow': 1,
    'superuser': 2,
    'meta': 3,
    'serverfault': 4,
    'mathoverflow': 5
}
</code></pre>

<p>To check if there are more than one key available in the above dictionary, I will do something like:</p>

<pre><code>'stackoverflow' in sites and 'serverfault' in sites
</code></pre>

<p>The above is maintainable with only 2 key lookups.  Is there a better way to handle checking a large number of keys in a very big dictionary?</p>
