title: Return value from map.forEach in dart?
body: <p>I want to search for a value in a <code>Map</code>.</p>
  
  <pre><code>Map&lt;String, dynamic&gt; map;
  dynamic someThing;
  
  map.forEach((String key, dynamic value) {
    if (value == someThing) {
      return value;
    }
  });
  </code></pre>
  
  <p>but I get this warning:</p>
  
  <blockquote>
    <p>Don't assign to <code>void.dart(void_checks)</code></p>
  </blockquote>
  
  <p>how can I do it without getting this warning?</p>