code: def _validate(self):
          
          try:
              self._resolve_workspace()
              if 'mets_unique_identifier' not in self.skip:
                  self._validate_mets_unique_identifier()
              if 'mets_file_group_names' not in self.skip:
                  self._validate_mets_file_group_names()
              if 'mets_files' not in self.skip:
                  self._validate_mets_files()
              if 'pixel_density' not in self.skip:
                  self._validate_pixel_density()
              if 'page' not in self.skip:
                  self._validate_page()
          except Exception as e: # pylint: disable=broad-except
              self.report.add_error("Failed to instantiate workspace: %s" % e)
              #  raise e
          return self.report
docs: Actual validation.