title: Find dictionary items whose key matches a substring
body: <p>I have a large dictionary constructed like so:</p>
  
  <pre><code>programs['New York'] = 'some values...' 
  programs['Port Authority of New York'] = 'some values...' 
  programs['New York City'] = 'some values...'
  ...
  </code></pre>
  
  <p>How can I return all elements of <code>programs</code> whose key mentions "new york" (case insensitive)? In the example above, I would want to get all the three items.</p>
  
  <p><strong>EDIT:</strong> The dictionary is quite large and expected to get larger over time.</p>