docs: def supports_version(self, guid_set):
          """
          Returns whether a GUID set in for_appversions format is compatbile with
          the current supported applications list.
          """
  
          # Don't let the test run if we haven't parsed install.rdf yet.
          if self.supported_versions is None:
              raise Exception('Early compatibility test run before install.rdf '
                              'was parsed.')
  
          return self._compare_version(requirements=guid_set,
                                       support=self.supported_versions)