title: How do I access keys by value in a Perl hash of hashes?
body: <p>I've hash of hash like this:</p>
  
  <pre><code>$hashtest{ 1 } = {
    0 =&gt; "A",
    1 =&gt; "B",
    2 =&gt; "C"
  };
  </code></pre>
  
  <p>For example, how can I take the value of B of hash{ 1 }?</p>
  
  <pre><code>$hashtest{'B'}{1}
  </code></pre>