Problem with constructing a tree

Hi,
I have a problem where I need to construct a tree from an xml file:
The xml file looks like this:
<feeAgreement>
     <feeClauses clauseid="1" rootclause="false">
          <computationUnit name="xxxx">
                  <complexComputationUnit clauseid="2"/>
          </computationUnit>
     </feeClauses>
    <feeClauses clauseid="2" rootclause="false">
          <computationUnit name="yyyy">
                 <complexComputationUnit clauseid="3"/>
          </computationUnit>
     </feeClauses>
    <feeClauses clauseid="3" rootclause="false">
          <computationUnit name="zzzz">
               <complexComputationUnit clauseid="1"/>
          </computationUnit>
     </feeClauses>
</feeAgreement>

Now, I would like to typically use recursion to construct the tree, starting
at the first feeClauses element. When I get to the complexComputationUnit
element's clauseid attribute, I would like to go over and find the clause
with the clauseid specified here.
The problem is, I need to know if the clause is already present, as in the
case of clause 3, which refers to clause 1. Here, I need not get the first
clause.
I cannot seem to think of a way of checking while transforming whether I
have the clause already in the transformed part.
Any help would be greatly appreciated.
Thanks,
Yashdeep Patil.


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