title: find item inside list of list
body: <p>I have a list of customers having another list within customers called series. My series can be <code>null</code> or contain data.
  How can I find any item matching series value. I have tried the two mehods below  but with no success.</p>
  
  <pre><code>results = customers.Where(d =&gt; d.Series.Any(s =&gt; s.Contains("item")));
  
  results = customers.Where(d =&gt; d.Series.Count() != 0).Where(s =&gt; s.Series.Contains("item"));
  </code></pre>
  
  <p>Thanks!</p>