title: How do you find an element index in a Collection<T> inherited class?
body: <p>How do you find the index of an element in a Collection inherited class?</p>
  
  <pre><code>public class MyCollection : Collection&lt;MyClass&gt;
  {
     // implementation here
  }
  </code></pre>
  
  <p>I tried to use .FindIndex on the collection but no success:</p>
  
  <pre><code> int index = collectionInstance.FindIndex(someLambdaExpression);
  </code></pre>
  
  <p>Any other ways to achieve this?</p>