3、创建一个名为"BankAccount"的类，该类包含私有属性"accountNumber"和"balance"， 以及公有方法"getAccountNumber"、"getBalance"、"deposit"和"withdraw"来获取和操作私有属性的值。 在类的外部创建一个"BankAccount"对象并进行一些存款和取款操作，然后打印账户号码和余额。

代码如下：

class BankAccount:
    def __init__(self, accountNumber, balance):
        self.__accountNumber = accountNumber
        self.__balance = balance

    def getAccountNumber(self):
        return self.__accountNumber

    def getBalance(self):
        return self.__balance

    def deposit(self, amount):
        self.__balance += amount

    def withdraw(self, amount):
        if self.__balance >= amount:
            self.__balance -= amount
        else:
            print("Sorry, insufficient funds.")

# 创建一个BankAccount对象
myAccount = BankAccount("1234567890", 5000)

# 存款1000元
myAccount.deposit(1000)

# 取款2000元
myAccount.withdraw(2000)

# 打印账户号码和余额
print("Account Number:", myAccount.getAccountNumber())
print("Balance:", myAccount.getBalance())

输出结果：

Account Number: 1234567890
Balance: 4000