# Extracts a collection of birth dates from the user and determines
# if each individual is at least 21 years of age.
from date import Date

def main():
 # Date before which a person must have been born to be 21 or older.
 bornBefore = Date(6, 1, 1988)

 # Extract birth dates from the user and determine if 21 or older.
 date = promptAndExtractDate()
 while date is not None :
 if date <= bornBefore :
 print( "Is at least 21 years of age: ", date )
 date = promptAndExtractDate()
 
# Prompts for and extracts the Gregorian date components. Returns a
# Date object or None when the user has finished entering dates.
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 )

# Call the main routine.
main()