new_contents: #!/usr/bin/env python
  #
  #    verify_schema.py: simple LXML wrapper for checking XML against
  #                      a RelaxNG schema.
  #
  #    Copyright (C) 2014 VyOS Development Group <maintainers@vyos.net>
  #
  #    This library is free software; you can redistribute it and/or
  #    modify it under the terms of the GNU Lesser General Public
  #    License as published by the Free Software Foundation; either
  #    version 2.1 of the License, or (at your option) any later version.
  #
  #    This library is distributed in the hope that it will be useful,
  #    but WITHOUT ANY WARRANTY; without even the implied warranty of
  #    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  #    Lesser General Public License for more details.
  #
  #    You should have received a copy of the GNU Lesser General Public
  #    License along with this library; if not, write to the Free Software
  #    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
  #    USA
  
  import sys
  from lxml import etree as ET
  
  if len(sys.argv) < 2:
      print("Usage: {0} <RelaxNG schema file> <XML file>".format(sys.argv[0]))
      sys.exit(1)
  
  schema = sys.argv[1]
  xml_source = sys.argv[2]
  
  xml_tree = ET.parse(xml_source)
  relaxng_xml = ET.parse(schema)
  validator = ET.RelaxNG(relaxng_xml)
  
  if not validator.validate(xml_tree):
      print(validator.error_log)
      print("File {0} does not match the schema!".format(xml_source))
      sys.exit(1)
  
  
subject: Add a simple schema validation script based on LXML.