通过一个例子，说明Python的责任链设计模式有什么优缺点

class Handler:
    def __init__(self, successor=None):
        self._successor = successor

    def handle_request(self, request):
        if self.can_handle(request):
            self.process(request)
        else:
            if self._successor:
                self._successor.handle_request(request)
            else:
                print("No handler available for the request.")

    def can_handle(self, request):
        # 定义哪些请求可以被当前处理器处理
        pass

    def process(self, request):
        # 处理请求
        print(f"Request {request} processed by {self.__class__.__name__}")

# 具体的处理者
class ManagerA(Handler):
    def can_handle(self, request):
        return request <= 5000  # 假设经理A负责审批5000元以下的报销

class ManagerB(Handler):
    def __init__(self):
        super().__init__(successor=Supervisor())

    def can_handle(self, request):
        return request > 5000 and request <= 10000  # 假设经理B负责5000到10000元

class Supervisor(Handler):
    def can_handle(self, request):
        return request > 10000  # 假设主管负责审批10000元以上的报销

# 创建责任链
manager_a = ManagerA(ManagerB())
manager_b = ManagerB()
supervisor = Supervisor()

# 提交报销单据
manager_a.handle_request(4500)  # 经理A处理
manager_a.handle_request(7000)  # 经理B处理
manager_a.handle_request(12000) # 主管处理