class Account(object):
    """A bank account that allows deposits and withdrawals."""

    interest = 0.02

    def __init__(self, account_holder):
        self.balance = 0
        self.holder = account_holder

    def deposit(self, amount):
        """Increase the account balance by amount and return the new balance."""
        self.balance = self.balance + amount
        return self.balance

    def withdraw(self, amount):
        """Decrease the account balance by amount and return the new balance."""
        if amount > self.balance:
            return 'Insufficient funds'
        self.balance = self.balance - amount
        return self.balance


class CheckingAccount(Account):
    """A bank account that charges for withdrawals."""

    withdraw_fee = 1
    interest = 0.01

    def withdraw(self, amount):
        return Account.withdraw(self, amount + self.withdraw_fee)


class SavingsAccount(Account):
    """A bank account that charges for deposits."""

    deposit_fee = 2

    def deposit(self, amount):
        return Account.deposit(self, amount - self.deposit_fee)


class AsSeenOnTVAccount(CheckingAccount, SavingsAccount):
    """A bank account that charges for everything."""

    def __init__(self, account_holder):
        self.holder = account_holder
        self.balance = 1           # A free dollar!

supers = [c.__name__ for c in AsSeenOnTVAccount.mro()]