def deactivate(self, manager):
		for system in self.systems:
			manager.event_dispatcher.remove_handlers(system)
		super(World, self).deactivate(manager)
Returns the value of the field name for this instance. If the field is
dataset/ETHPy150Open caseman/grease/grease/world.py/World.deactivate--crossover with--dataset/ETHPy150Open CollabQ/CollabQ/vendor/django/db/models/base.py/Model.serializable_value