code: def from_uuid(self, uuid, session=None):
          '''Retrieve a :class:`Model` from its universally unique identifier
  ``uuid``. If the ``uuid`` does not match any instance an exception will raise.
  '''
          elems = uuid.split('.')
          if len(elems) == 2:
              model = get_model_from_hash(elems[0])
              if not model:
                  raise Model.DoesNotExist(
                      'model id "{0}" not available'.format(elems[0]))
              if not session or session.router is not self:
                  session = self.session()
              return session.query(model).get(id=elems[1])
          raise Model.DoesNotExist('uuid "{0}" not recognized'.format(uuid)f from_uuid(self, uuid, session=None):
          '''Retrieve a :class:`Model` from its universally unique identifier
  ``uuid``. If the ``uuid`` does not match any instance an exception will raise.
  '''
          elems = uuid.split('.')
          if len(elems) == 2:
              model = get_model_from_hash(elems[0])
              if not model:
                  raise Model.DoesNotExist(
                      'model id "{0}" not available'.format(elems[0]))
              if not session or session.router is not self:
                  session = self.session()
              return session.query(model).get(id=elems[1])
          raise Model.DoesNotExist('uuid "{0}" not recognized'.format(uuid))
docs: Retrieve a :class:`Model` from its universally unique identifier
  ``uuid``. If the ``uuid`` does not match any instance an exception will raise.