Función para validar un CBU

gistfile1.py

def validate_cbu(cbu):
    """
    Validation function for the CBU (Clave Bancaria Unica)

    Arguments:
    cbu   -- String or int of 22 characters
    """
    cbu = str(cbu)
    if len(cbu) == 22:

        sum1 = sum2 = 0
        # Multipliers used to verify the CBU
        multiplier = '7139713'
        multiplier_2 = '3971397139713'

        # We need to sum and multiply with the multiplier the first 7 characters
        for i, num in enumerate(cbu[:7]):
            sum1 += int(num) * int(multiplier[i])

        # We need to sum and multiply with the multiplier from character 8 to 21
        for i, num in enumerate(cbu[8:21]):
            sum2 += int(num) * int(multiplier_2[i])

        # If 10 minus the last character of sum1 is different from CBU char 8
        # or if 10 minus the last character of sum2 is different from last CBU char
        # we return False
        if 10-int(str(sum1)[-1]) != int(cbu[7]) or 10-int(str(sum2)[-1]) != int(cbu[21]):
            return False

        return True

    return False