def has_valid_checksum(self, number):
        multiple_table = (6, 5, 7, 2, 3, 4, 5, 6, 7)
        result = 0
        for i in range(len(number)-1):
            result += int(number[i]) * multiple_table[i]

        result %= 11
        if result == int(number[-1]):
            return True
        else:
            return False
Calculates a checksum with the provided algorithm.
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/contrib/localflavor/pl/forms.py/PLNIPField.has_valid_checksum