title: How to specify the root namespace for a variable when you are in a namespace
body: <p>It works when I do:</p>
  
  <pre><code>namespace UnitTesting {class UnitTest_1;}
  
  namespace NLa
  {
      class Search
      {
         friend class UnitTesting::UnitTest_1;
      }
  }
  </code></pre>
  
  <p>But what if <code>class UnitTest_1</code> is not in a namespace ?</p>