title: Python - Validation with multiple schemas using lxml
body: <p>I'm working with a schema that was built by a third party and I'd like to validate it with lxml. The problem is that such a schema is split over different xsd files, which reference themselves.</p>
  
  <p>For example, a file called "extension.xsd" (which builds upon the "master" schema) has a line like:</p>
  
  <pre><code>&lt;redefine schemaLocation="master.xsd"&gt;
  </code></pre>
  
  <p>If I try to validate it with lxml (parsing, then using <code>XMLSchema</code> then validating another document which I know is valid already), I only get validation using "extension" and not "master": in  other words, the validation fails (because in the XML file there are elements only present in "master" and not in "extension").</p>
  
  <p>How can I solve (or work around) this issue? Thanks!</p>