"""simple docstring"""


def      lowerCamelCase_					(   __lowerCAmelCase							)				->   bool:




						'''simple docstring'''



						return credit_card_number.startswith(("34", "35", "37", "4", "5", "6")							)





def      lowerCamelCase_					(   __lowerCAmelCase							)				->   bool:




						'''simple docstring'''



						lowerCamelCase__   =credit_card_number
						lowerCamelCase__   =0
						lowerCamelCase__   =len(_lowercase							) - 2
						for i in range(_lowercase  ,       -1  ,       -2							):
												#  double the value of every second digit
												lowerCamelCase__   =int(cc_number[i]							)
												digit *= 2
												# If doubling of a number results in a two digit number
												# i.e greater than 9(e.g., 6 × 2 = 12),
												# then add the digits of the product (e.g., 12: 1 + 2 = 3, 15: 1 + 5 = 6),
												# to get a single digit number.
												if digit > 9:
																		digit %= 10
																		digit += 1
												lowerCamelCase__   =cc_number[:i] + str(_lowercase							) + cc_number[i + 1 :]
												total += digit

						# Sum up the remaining digits
						for i in range(len(_lowercase							) - 1  ,       -1  ,       -2							):
												total += int(cc_number[i]							)

						return total % 10 == 0





def      lowerCamelCase_					(   __lowerCAmelCase							)				->   bool:




						'''simple docstring'''



						lowerCamelCase__   =F'''{credit_card_number} is an invalid credit card number because'''
						if not credit_card_number.isdigit():
												print(F'''{error_message} it has nonnumerical characters.'''							)
												return False

						if not 13 <= len(_lowercase							) <= 16:
												print(F'''{error_message} of its length.'''							)
												return False

						if not validate_initial_digits(_lowercase							):
												print(F'''{error_message} of its first two digits.'''							)
												return False

						if not luhn_validation(_lowercase							):
												print(F'''{error_message} it fails the Luhn check.'''							)
												return False

						print(F'''{credit_card_number} is a valid credit card number.'''							)
						return True


if __name__ == "__main__":
	import doctest

	doctest.testmod()
	validate_credit_card_number('4111111111111111')
	validate_credit_card_number('32323')






import string






def 		_A		(		_lowercase )					-> None:


     """simple docstring"""


     for key in range(len(string.ascii_uppercase ) ):
          __UpperCamelCase =			''
          for symbol in message:
               if symbol in string.ascii_uppercase:
                    __UpperCamelCase =			string.ascii_uppercase.find(_lowercase )
                    __UpperCamelCase =			num - key
                    if num < 0:
                         __UpperCamelCase =			num + len(string.ascii_uppercase )
                    __UpperCamelCase =			translated + string.ascii_uppercase[num]
               else:
                    __UpperCamelCase =			translated + symbol
          print(f'''Decryption using Key #{key}: {translated}''' )






def 		_A		(		)					-> None:


     """simple docstring"""


     __UpperCamelCase =			input('Encrypted message: ' )
     __UpperCamelCase =			message.upper()
     decrypt(_lowercase )


if __name__ == "__main__":
    import doctest

    doctest.testmod()
    main()


