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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-continue>
    <allfileusages gafcontinue="BE109_Fall09_Mod1_Day8_to_POST.pdf|5939" />
  </query-continue>
  <query>
    <pages>
      <page pageid="2835" ns="0" title="Optics Bootcamp" />
      <page pageid="5762" ns="0" title="20.109(F08): Mod 3 Day 1 Growth of phage materials" />
      <page pageid="5939" ns="0" title="20.109(F09): Fall 2009 schedule" />
      <page pageid="8487" ns="0" title="20.109(F17): Fall 2017 Schedule" />
      <page pageid="8757" ns="0" title="20.109(S18): Spring 2018 schedule" />
      <page pageid="9014" ns="0" title="20.109(F18): Fall 2018 schedule" />
      <page pageid="9270" ns="0" title="20.109(S19): Spring 2019 schedule" />
    </pages>
  </query>
</api>