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 afcontinue="Biocore_2018.jpg|4690" />
  </query-continue>
  <query>
    <allfileusages>
      <f fromid="4263" ns="6" title="File:BIST-Portada-Cursos-BioStatistics-2.jpg" />
      <f fromid="4263" ns="6" title="File:BIST Module3 practicum.zip" />
      <f fromid="4696" ns="6" title="File:BIST Module3 practicum.zip" />
      <f fromid="4263" ns="6" title="File:BIST Module5 hands on.zip" />
      <f fromid="4696" ns="6" title="File:BIST Module5 hands on.zip" />
      <f fromid="5016" ns="6" title="File:Bce00230.nativeT samelayerF.multi.png" />
      <f fromid="4537" ns="6" title="File:Bean-01.jpg" />
      <f fromid="4538" ns="6" title="File:Bean-01.jpg" />
      <f fromid="3985" ns="6" title="File:BioCore Stat 2015.pptx" />
      <f fromid="3423" ns="6" title="File:BioCore advisory mtg June 22 2015.pptx" />
    </allfileusages>
  </query>
</api>