title: When configuring a binary tree, is it possible to just increase the height to a null node?
body: <p>For example, can such a binary tree exist?</p>
  
  <pre><code>     A        
     /   \      
    N     N     
   / \   / \  
  N   B C   N 
  </code></pre>
  
  <p>It's just a question out of my curiosity.</p>