title: PHP: add/edit output tags with DomXPath
body: <p>I should be able to modify the output obtained with the following query: </p>
  
  <pre><code>$ods22_tmp_t =$finder-&gt;query("//*[contains(@class, 'PPToggle')]");
  </code></pre>
  
  <p>the output is as follows:</p>
  
  <pre><code>              &lt;tr class="PPToggle" CO="8465"&gt;
                      &lt;td PT="0" PABloccato="True" Validato="False" MeseValidato="False"&gt;&lt;div title="HD09001300 dalle ore 09:00 alle ore 13:00" class="cellePiano" PT="1428" ColoreTesto="#000000" ColoreSfondo=""&gt;
                          HD09001300
                      &lt;/div&gt;&lt;div title="HD14001800 dalle ore 14:00 alle ore 18:00" class="cellePiano" PT="142" ColoreTesto="#000000" ColoreSfondo=""&gt;
                          HD14001800
                      &lt;/div&gt;&lt;/td&gt;&lt;td PT="0" PABloccato="True" Validato="False" MeseValidato="False"&gt;&lt;div title="HD10001400 dalle ore 10:00 alle ore 14:00" class="cellePiano" PT="142219" ColoreTesto="#000000" ColoreSfondo=""&gt;
                          HD10001400
                      &lt;/div&gt;&lt;div title="HD15001900 dalle ore 15:00 alle ore 19:00" class="cellePiano" PT="142820" ColoreTesto="#000000" ColoreSfondo=""&gt;
                          HD15001900
                      &lt;/div&gt;&lt;/td&gt;&lt;td PT="0" PABloccato="True" Validato="False" MeseValidato="False"&gt;&lt;div title="HD13001700 dalle ore 13:00 alle ore 17:00" class="cellePiano" PT="142882" ColoreTesto="#000000" ColoreSfondo=""&gt;
                          HD13001700
                      &lt;/div&gt;&lt;div title="HD18002200 dalle ore 18:00 alle ore 22:00" class="cellePiano" PT="14287" ColoreTesto="#000000" ColoreSfondo=""&gt;
                          HD18002200
                      &lt;/div&gt;&lt;/td&gt;
                  &lt;/tr&gt;
  </code></pre>
  
  <p>I would like to add this tag between TR and TD: </p>
  
  <pre><code>&lt;th&gt;Operator&lt;/th&gt;
  </code></pre>
  
  <p>How can I specify that I want to add a tag between two in particular? </p>