title: in a method which produces lazy list, what happens if i return nothing?
body: <p>it seems this code is valid. I am wondering what if <code>getTest(1)</code></p>
  
  <pre><code>    IEnumerable&lt;int&gt; getTest(int n)
      {
          if (n == 0)
              yield return 1;
          else
              ;
      }
  </code></pre>