python嵌套类

我的代码版本，带有注释：

## 1. CamelCasing for classes#class Account:    def __init__(self):        # 2. to refer to the inner class, you must use self.Bank        # 3. no need to use an inner class here        self.bank = self.Bank()    class Bank:        def __init__(self): self.balance = 100000        # 4. in your original pre, you had a method with the same name as         #    the attribute you set in the constructor. That meant that the         #    method was replaced with a value every time the constructor was         #    called. No need for a method to do a simple attribute lookup. This        #    is Python, not Java.        def withdraw(self, amount): self.balance -= amount        def deposit(self, amount): self.balance += amounta = Account()print(a.bank.balance)