def pandigital_primes(digits=7):
    for p in primes_upto(int(('9' * digits))):
        if is_pandigital(p):
            (yield p)
def pandigital_primes(digits=7):
    for p in primes_upto(int(('9' * digits))):
        if is_pandigital(p):
            (yield p)