# Debit card program # ------------------------- # Subprograms # ------------------------- def validate_number(number_on_card): valid = True number_of_characters = len(number_on_card) if number_of_characters == 16 or number_of_characters == 19: for character in number_on_card: if not character.isdigit() and character != " ": valid = False else: valid = False return valid def input_card_details(): valid_card = False while not valid_card: number_input = input("Enter the 16 digit number: ") valid_card = validate_number(number_input) # ------------------------- # Main program # ------------------------- input_card_details() print("Card details valid.")