def nullable_timestamps(self):
        self.timestamp('created_at').nullable()
        self.timestamp('updated_at').nullable()
Registers a new event listener with the specified activation method
dataset/ETHPy150Open sdispater/orator/orator/schema/blueprint.py/Blueprint.nullable_timestamps--crossover with--dataset/ETHPy150Open rwl/muntjac/muntjac/event/method_event_source.py/IMethodEventSource.addListener