title: how to parent tag with nested tag
body: <p>I have an XML File that looks like this:</p>
  
  <pre><code>&lt;SNS&gt;
  &lt;SN&gt;aaaa&lt;/SN&gt;
  &lt;SN&gt;bbbb&lt;/SN&gt;
  &lt;LN&gt;cccc&lt;/LN&gt;
  &lt;SN&gt;dddd&lt;/SN&gt;
  &lt;SN&gt;eeee&lt;/SN&gt;
  &lt;LN&gt;ffff&lt;/LN&gt;
  &lt;/SNS&gt;
  </code></pre>
  
  <p>Required Output:</p>
  
  <pre><code>&lt;SN&gt;aaaa&lt;/SN&gt;
  &lt;LN&gt;cccc&lt;/LN&gt;
  &lt;SN&gt;bbbb&lt;/SN&gt;
  &lt;LN&gt;cccc&lt;/LN&gt;
  &lt;SN&gt;dddd&lt;/SN&gt;
  &lt;LN&gt;ffff&lt;/LN&gt;
  &lt;SN&gt;eeee&lt;/SN&gt;
  &lt;LN&gt;ffff&lt;/LN&gt;
  </code></pre>
  
  <p>How to add every <code>&lt;SN&gt;</code> tag with <code>&lt;LN&gt;</code>?</p>