Is it possible to validate an XML file against XSD 1.1 in Python?

I want validate an XML file against an XSD file using lxml.XMLSchema. But the problem is the XSD is in 1.1. So it doesn't work.

This is a part of the XML:

<?xml version="1.0" encoding="UTF-8"?>
<dictionary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:noNamespaceSchemaLocation="!!assert.xsd">
  <SizeType>10</SizeType>
</dictionary>

And this is its XSD file:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           elementFormDefault="qualified">
  <xs:element name="SizeType">
    <xs:simpleType>
      <xs:restriction base="xs:integer">
        <xs:assertion test="$value = 10"/>
      </xs:restriction>
    </xs:simpleType>
  </xs:element>
</xs:schema>

So, is it possible to validate an XML file against a XSD file that uses xs:assertion statements (1.1)?

I think this question is closely related to this: lxml with schema 1.1

2022 update

Yes, starting in 2019 it finally became possible to validate XML against XSD 1.1 in Python.

Davide Brunato added XSD 1.1 support to xmlschema (v1.0.14).

_{^{Thanks to @Alex for pointing out the update.}}

2013 original answer

As of early November 2013, only the following XML processors support XSD 1.1:

• Xerces-J with PsychoPath XPath 2.0
• Saxon EE
• Altova

There is no XML parser written in Python that validates against XSD 1.1 yet.