def del_attribute(instance, key):
 (state, dict_) = (instance_state(instance), instance_dict(instance))
 state.manager[key].impl.delete(state, dict_)

def del_attribute ( instance , key ) : ( state , dict_ ) = ( instance_state ( instance ) , instance_dict ( instance ) ) state . manager [ key ] . impl . delete ( state , dict_ )
delete the value of an attribute .