title: Check if two dictionaries are disjoint
body: <p>Is there an easier/faster way to find out if two dictionaries are disjoint than calculating their intersection?</p>
  <p>For the intersection I found <a href="https://stackoverflow.com/questions/18554012/intersecting-two-dictionaries-in-python">this answer</a>, so the disjoint-test would look like this:</p>
  <pre><code>def dicts_disjoint(a, b):
      keys_a = set(a.keys())
      keys_b = set(b.keys())
      intersection = keys_a &amp; keys_b
      return not len(intersection)
  </code></pre>
  <p>However I think this is inefficient since it always calculates the whole intersection (no short-circuit quit).</p>
  <p>Any better ideas?</p>