oop conceps

bank_account.py

class BANK_ACCOUNT:
    """Bank account
        has balance, and withdraw and deposit functions"""
    def __init__(self):
        self.balance = 0
    def deposit(self, amount):
        """adds money to the balance"""
        self.balance += amount
    def __str__(self):
        return "Balance is: $" + str(format(self.balance,".2f"))
class CHILDACCOUNT(BANK_ACCOUNT):
    def __init__(self):
       super().__init__()
    def withdraw(self, amount):
        if amount>20:
            print('Too much money')
            return False
        else:
            self.balance=self.balance-amount
            return True
b = BANK_ACCOUNT()
print(b)
b.deposit(47.384)
print(b)
print(b.__doc__)
print(b.deposit.__doc__)
c=CHILDACCOUNT()
print(c)
c.deposit(100)
print(c)
c.withdraw(50)
print(c)
c.withdraw(20)
print(c)