Where is this variable defined?
<p>reading diveintopython3 came upon this and can't deconstruction into smaller bits i understand. </p>

<pre><code>&gt;&gt;&gt; a_dict = {'a': 1, 'b': 2, 'c': 3}                        
&gt;&gt;&gt; {value:key for key, value in a_dict.items()}             
&gt;&gt;&gt; {1: 'a', 2: 'b', 3: 'c'}
</code></pre>

<p>a_dict.items() creates a list. But value in a_dict.items() doesn't make sense to me as value isn't defined...</p>

<p>whats going on here?</p>
