shorthand way to create dictionary key if it does not exist
<p>I have a dictionary of zoo animals. I want to put it into the dictionary in a nested dictionary but get a KeyError because that particular species has not been added to the dictionary.</p>

<pre><code>def add_to_world(self, species, name, zone = 'retreat'):
    self.object_attr[species][name] = {'zone' : zone}
</code></pre>

<p>Is there a shortcut to checking if that species is in the dictionary and create it if it is not or do i have to do it the long way and manually check if that species has been added?</p>
