Remove duplicates from a list

Hi,
  I'm trying to convert xml to html.
  
  A part of my xml looks like this:
  
 <location>
   <state>xxxx</state>
 </location>
  
 <location>
    <state>yyyy</state>
 </location>
 
  <location>
    <state>xxxx</state>
 </location>
 
 The desired output is:
 
   xxxx
   yyyy
   
 That is, duplicate values of state should not be printed.
 Can this be done? 
 
 Thanks.
 
 Minita


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