re okay for simple expressions. This includes list
          comprehensions, dictionary comprehensions, set comprehensions, etc. Generator
          expressions are neat ways to concisely create lists. Simple ones are fine:</p>

        <blockquote>
          <p>Good</p>
        </blockquote>

        <pre><code>ex = [x*x for x in range(10)]
L = [pair[0] + pair[1]
     for pair in pairs
     if len(pair) == 2]</code></pre>

        <p>However, complex generator expressions are very hard to read, even
      