fromrandomimportchoicefrompyknowimport*classLight(Fact):"""Info about the traffic light."""passclassRobotCrossStreet(KnowledgeEngine):@Rule(Light(color='green'))defgreen_light(self):print("Walk")@Rule(Light(color='red'))defred_light(self):print("Don't walk")@Rule(AS.light<<Light(color=L('yellow')|L('blinking-yellow')))defcautious(self,light):print("Be cautious because light is",light["color"])

>>>engine=RobotCrossStreet()>>>engine.reset()>>>engine.declare(Light(color=choice(['green','yellow','blinking-yellow','red'])))>>>engine.run()Becautiousbecauselightisblinking-yellow