gistfile1.py

class Credit():
    charges = []
    history = {}

    def __init__(value):
        self.charges.append(value)

    def balance():
      print sum(self.charges)

    def charge(n):
        self.history[time.time()] = n

    def estimate_interest(n):
        """estimate interest charges if payment activity on the account"""
        total = self.balance()
        print total - n % 17.5%

    def make_payment(n):
      values = self.charges
      del values[n]
      print values