title: searching and retrieving set elements containing partial string when set is large
body: <p>I am working on a large dataset ~1 billion lines. I have them as a <code>set</code>.</p>
  
  <p>My task is to pick out those lines that contain the work <code>'risk'</code>.</p>
  
  <p>So, I used </p>
  
  <pre><code>a = [sent for sent in sent_set if 'risk' in sent] 
  </code></pre>
  
  <p>Is there a better, faster (more pythonic) way of doing this? </p>