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HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
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<?xml version="1.0"?>
<api>
  <query>
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      <p pageid="647" ns="0" title="Main Page" revid="2970" />
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      <p pageid="879" ns="0" title="The Discount Option To Gamble On The Web" revid="3097" />
      <p pageid="1" ns="0" title="main Page" revid="2418" />
    </unreviewedpages>
  </query>
</api>