import re

class Luhn:
    def __init__(self, card_num):

        pattern = re.compile(r'\s+')
        card_num = re.sub(pattern, '', card_num)

        if not card_num.isnumeric() or len(card_num) < 2:
            self.is_valid = False
        else:

            checksum = 0

            for i, ch in enumerate(reversed(card_num)):

                x = int(ch)

                if i % 2:
                    x *= 2

                    if x > 9:
                        x -= 9

                checksum += x

            self.is_valid = not (checksum % 10)

    def valid(self):
        return self.is_valid