@classmethod
def restore(self, id, backend=None):
    'Restore previously saved group result.'
    return (backend or (self.app.backend if self.app else current_app.backend)).restore_group(id)
Restore previously saved group result.
@classmethod
def restore(self, id, backend=None):
    
    return (backend or (self.app.backend if self.app else current_app.backend)).restore_group(id)