<filename>Chapter2/R-2/5.py
def make payment(self, amount):
    """Process customer payment that reduces balance."""
    if not isinstance(amount, (int, float)):
        raise TypeError('amount is not a number')

    self.balance −= amount

<filename>Chapter2/R-2/5.py
def make payment(self, amount):
    """Process customer payment that reduces balance."""
    if not isinstance(amount, (int, float)):
        raise TypeError('amount is not a number')

    self.balance −= amount

Process customer payment that reduces balance.