title: Use case for nested/multiple list comprehensions or generator expressions. When is it more elegant?
body: <p>I see this kind of thing sometimes:</p>
  
  <pre><code>(k for k in (j for j in (i for i in xrange(10))))
  </code></pre>
  
  <p>Now this really bends my brain, and I would rather it wasn't presented in this way.</p>
  
  <p>Are there any use-cases, or examples of having used these nested expressions where it was more elegant and more readable than if it had been a nested loop?</p>
  
  <p><strong>Edit:</strong> Thanks for the examples of ways to simplify this. It's not actually what I asked for, I was wondering if there were any times when it was elegant.</p>