title: How can I create a repeatable signature of a data structure?
body: <p>I have a situation where I want to create a signature of a data structure:</p>
  
  <pre><code>my $signature = ds_to_sig(
    { foo   =&gt; 'bar',
      baz   =&gt; 'bundy',
      boing =&gt; undef,
      number =&gt; 1_234_567,
    }
  );
  </code></pre>
  
  <p>The aim should be that if the data structure changes then so should the signature.</p>
  
  <p>Is there an established way to do this?</p>