





def      _A       (		SCREAMING_SNAKE_CASE     :   str						):





  """simple docstring"""



  return credit_card_number.startswith(("34", "35", "37", "4", "5", "6")						)
def      _A       (		SCREAMING_SNAKE_CASE     :   str						):





  """simple docstring"""



  a__	:					Tuple										=credit_card_number
  a__	:					Union[str, Any]										=0
  a__	:					List[str]										=len(SCREAMING_SNAKE_CASE						) - 2
  for i in range(SCREAMING_SNAKE_CASE       ,       -1       ,       -2						):
    #  double the value of every second digit
    a__	:					List[Any]										=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
    a__	:					List[str]										=cc_number[:i] + str(SCREAMING_SNAKE_CASE						) + cc_number[i + 1 :]
    total += digit

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

  return total % 10 == 0
def      _A       (		SCREAMING_SNAKE_CASE     :   str						):





  """simple docstring"""



  a__	:					List[Any]										=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(SCREAMING_SNAKE_CASE						) <= 16:
    print(f'''{error_message} of its length.'''						)
    return False

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

  if not luhn_validation(SCREAMING_SNAKE_CASE						):
    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""")













"""simple docstring"""





def  __A   (_SCREAMING_SNAKE_CASE     ,   _SCREAMING_SNAKE_CASE			)					->bool:





  """simple docstring"""


  return numa ^ numa < 0


if __name__ == "__main__":
  import doctest

  doctest.testmod()
