You are looking at the HTML representation of the XML format.
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.
See the complete documentation, or API help for more information.
<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages gafcontinue="Imbox_protection.png" />
  </query-continue>
  <query>
    <pages>
      <page ns="6" title="File:Disambig gray.svg" missing="" />
      <page ns="6" title="File:Edit-clear.svg" missing="" />
      <page ns="6" title="File:Https://www.b17.ru/foto/uploaded/upl 1497214532 51758.jpg" missing="" />
      <page ns="6" title="File:Icon tools.svg" missing="" />
      <page ns="6" title="File:Imbox notice.png" missing="" />
      <page pageid="635" ns="6" title="File:CNA students(4th) with instructors.jpeg" />
      <page pageid="859" ns="6" title="File:District 49 Flat-Color.png" />
      <page pageid="72" ns="6" title="File:Falcon High School logo.png" />
      <page pageid="787" ns="6" title="File:Husky1.jpg" />
      <page pageid="428" ns="6" title="File:Icon tools.png" />
    </pages>
  </query>
</api>