def add_trigger!(trigger)
	        raise PbwArgumentError('Invalid trigger') unless trigger
	        return false if has_trigger?(trigger)
	        self.triggers << trigger
	        save!
	        trigger.after_add(self)
	        self
	    end
def add_trigger!(trigger)
	        raise PbwArgumentError('Invalid trigger') unless trigger
	        return false if has_trigger?(trigger)
	        self.triggers << trigger
	        save!
	        trigger.after_add(self)
	        self
	    end
TRIGGERS