code: def schematron_validate(mets_doc, schematron=AM_SCT_PATH):
      
      if isinstance(schematron, six.string_types):
          schematron = get_schematron(schematron)
      is_valid = schematron.validate(mets_doc)
      report = schematron.validation_report
      return is_valid, report
docs: Validate a METS file using a schematron schema. Return a boolean
      indicating validity and a report as an ``lxml.ElementTree`` instance.