'Calculates a checksum with the provided algorithm.'

def has_valid_checksum(self, number):

    multiple_table = (1, 3, 7, 9, 1, 3, 7, 9, 1, 3, 1)
    result = 0
    for i in range(len(number)):
        result += (int(number[i]) * multiple_table[i])
    return ((result % 10) == 0)
