class SimpleRuleDST:
    def __init__(self):
        self.state = None
        self.init_session()

    def update(self, user_act=None):
        for intent, domain, slot, value in user_act:
            domain = domain.lower()
            intent = intent.lower()
            slot = slot.lower()
            value = slot.lower()

            if domain not in self.state['belief_state']:
                continue

            if intent == 'inform':
                if slot == 'none' or slot == '':
                    continue

                domain_dic = self.state['belief_state'][domain]

                if slot in domain_dic:
                    self.state['belief_state'][domain][slot] = value

            elif intent == 'request':
                if domain not in self.state['request_state']:
                    self.state['request_state'][domain] = {}
                if slot not in self.state['request_state'][domain]:
                    self.state['request_state'][domain][slot] = 0

        return self.state

    def init_session(self):
        self.state = None