outputting unknown amount of child elements

Given the following consisting of embedded elements with a common name:
<items>
   <item>Level 1
         <item>Level 2
               <item>A</item>
                 <item>B</item>
                       <item>Level 3
               --- etc.----
               </item>
           </item>
      <item>
</items>

How can I process this so all child elements (regardless of the depth) 
are outputted in a way that mirrors the structure structure of the 
original document. For example the uoutput may look something like this: 

Heading Level 1
   Heading Level 2
         A
         B
      Heading Level  3

I would find this straightforward if there was a fixed number of levels 
but in this case the amount varies and is unknown.
Thanks for your help

--
David Elsmore



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