code: def _issuer(self, entityid=None):
          
          if entityid:
              if isinstance(entityid, Issuer):
                  return entityid
              else:
                  return Issuer(text=entityid, format=NAMEID_FORMAT_ENTITY)
          else:
              return Issuer(text=self.config.entityid,
                            format=NAMEID_FORMAT_ENTITY)
docs: Return an Issuer instance