title: The opposite of Intersect()
body: <p>Intersect can be used to find matches between two collections, like so:</p>
  
  <pre><code>// Assign two arrays.
  int[] array1 = { 1, 2, 3 };
  int[] array2 = { 2, 3, 4 };
  // Call Intersect extension method.
  var intersect = array1.Intersect(array2);
  // Write intersection to screen.
  foreach (int value in intersect)
  {
      Console.WriteLine(value); // Output: 2, 3
  }
  </code></pre>
  
  <p>However what I'd like to achieve is the opposite, I'd like to list <strong>items from one collection that are missing from the other</strong>:</p>
  
  <pre><code>// Assign two arrays.
  int[] array1 = { 1, 2, 3 };
  int[] array2 = { 2, 3, 4 };
  // Call "NonIntersect" extension method.
  var intersect = array1.NonIntersect(array2); // I've made up the NonIntersect method
  // Write intersection to screen.
  foreach (int value in intersect)
  {
      Console.WriteLine(value); // Output: 4
  }
  </code></pre>