title: Iterate through 2 Lists
body: <p>I have a <code>List&lt;T1&gt;</code> of items and a second <code>List&lt;T2&gt;</code> of items.  Both lists are sorted alphabetically by the property A.  I know that the list of items in <code>List&lt;T2&gt;</code> are a subset of <code>List&lt;T1&gt;</code> and no items in <code>List&lt;T2&gt;</code> exists that don't exist in <code>List&lt;T1&gt;</code>.  </p>
  
  <p>I need to iterate through <code>List&lt;T1&gt;</code> and change a variable every time it matches a variable in <code>List&lt;T2&gt;</code>.  What is the fastest and best way to do this?  I am assuming I need to iterate through both lists but I know doing a nested foreach wouldn't make sense.</p>