def __set__(self, *args): raise db.DerivedPropertyError( 'Class-key is a derived property and cannot be set.')
def __set__(self, *args): raise db.DerivedPropertyError( 'Computed property %s cannot be set.' % self.name)
def __set__(self, model_instance, value): raise db.DerivedPropertyError("Cannot assign to a DerivedProperty")
def __set__(self, *args): raise db.DerivedPropertyError( 'Model-path is a derived property and cannot be set.')