from date import Date

def main():
 bornBefore = Date(6, 1, 1988)
 print(bornBefore)

 date = promptAndExtractDate()
 while date is not None:
 if date <= bornBefore:
 print("Is at least 21 yeas of age:", date)
 date = promptAndExtractDate()

def promptAndExtractDate():
 print("Enter a birth date.")
 month = int(input("month (0 to quit): "))
 if month == 0:
 return None
 else:
 day = int(input("day: "))
 year = int(input("year: "))
 return Date(month, day, year)

main()