<?xml version="1.0"?>
<sparql xmlns="http://www.w3.org/2005/sparql-results#">
   <head>
      <variable name="s"/>
      <variable name="p"/>
      <variable name="s"/>
   </head>
   <results>
      <result>
         <binding name="s">
            <uri>http://example.com/a</uri>
         </binding>
      </result>
   </results>
</sparql>