title: Does .NET have a way to check if List a contains all items in List b?
body: <p>I have the following method:</p>
  
  <pre><code>namespace ListHelper
  {
      public class ListHelper&lt;T&gt;
      {
          public static bool ContainsAllItems(List&lt;T&gt; a, List&lt;T&gt; b)
          {
              return b.TrueForAll(delegate(T t)
              {
                  return a.Contains(t);
              });
          }
      }
  }
  </code></pre>
  
  <p>The purpose of which is to determine if a List contains all the elements of another list. It would appear to me that something like this would be built into .NET already, is that the case and am I duplicating functionality?</p>
  
  <p>Edit: My apologies for not stating up front that I'm using this code on Mono version 2.4.2.</p>