title: Insert an element before and after a specific element in a List of strings
body: <p>Is it possible to insert to a list when a specific string appears.
  Example:</p>
  
  <pre><code>List=['north','south','east','west','south','united']
  </code></pre>
  
  <p>So for every time the string 'south' is presented the list will be insert an item <code>'canada'</code> before the element south in the list.</p>
  
  <pre><code>Results
  List=['north','canada','south','east','west','canada','south','united']
  </code></pre>
  
  <p>EDIT: I apologize for not being specific enough.  I need it to seek the specific characters.</p>
  
  <pre><code>List1=['north','&lt;usa&gt;23&lt;\usa&gt;','east','west','&lt;usa&gt;1942&lt;\usa&gt;','united']
  Result=['north','canada', '&lt;usa&gt;23&lt;\usa&gt;','east','west','canada','&lt;usa&gt;1942&lt;\usa&gt;','united']
  </code></pre>