title: Get keys by list of values
body: <p>I have a dictionary and a list of values such as:</p>
  <pre class="lang-py prettyprint-override"><code>dictionary = {'a': 1, 'b': 2, 'c': 3, 'd': 4}
  
  liste = [2, 3]
  </code></pre>
  <p>I would like:</p>
  <pre class="lang-py prettyprint-override"><code>result = ['b', 'c']
  </code></pre>
  <p>If I have a <strong>very large</strong> dictionary, what is the most optimal way to do this?</p>
  <p>The keys have unique values.</p>