projecteuler---->problem=32----Pandigital products

Problem 32

We shall say that an n-digit number is pandigital if it makes use of all the digits 1 to n exactly once; for example, the 5-digit
number, 15234, is 1 through 5 pandigital.

The product 7254 is unusual, as the identity, 39 × 186 = 7254, containing multiplicand, multiplier, and product is 1 through 9 pandigital.

Find the sum of all products whose multiplicand/multiplier/product identity can be written as a 1 through 9 pandigital.

HINT: Some products can be obtained in more than one way so be sure to only include it once in your sum.

def is_pandigital(*args, **kwargs):
    #将三个数转化成String并排序
    num = sorted(''.join(str(arg) for arg in args))
    print num
    print "kwargs = ",kwargs
    try:
        if kwargs['length'] and len(num) != kwargs['length']:
            return False
    except KeyError:
        pass

    for i in range(len(num)):
        if str(i+1) != str(num[i]):
            return False
    return True

def main():
    pandigitals = set()
    total = 0
    for multiplicand in range(1, 5000):
        for multiplier in range(1, 100):
            product = multiplicand * multiplier
            if is_pandigital(multiplicand, multiplier, product, length=9):
                pandigitals.add(product)
    print sum(pandigitals)
if __name__ == "__main__":
    main()