code: def _get_opus_maximum(self):
          
          label = """The opux maximum of a given author
                      that is, the only preserved work by that
                      author or the most known one."""
  
          opmax = self.session.get_resource(
              BASE_URI_TYPES % "opmax",
              self.session.get_class(surf.ns.ECRM['E55_Type'])
          )
          if opmax.is_present():
              return opmax
          else:
              opmax.rdfs_label.append(Literal(label, "en"))
              logger.debug("Created a new opus maximum type instance")
              opmax.save()
              return opmax
docs: Instantiate an opus maximum type.