random string generation with python

#!/usr/bin/python2.7

import random, string, sys
length=10
if len(sys.argv)>1:
        length=sys.argv[1]
rand_str = ''.join(random.choice(
                    string.ascii_lowercase
                    + string.ascii_uppercase
                    + string.digits)
               for i in range(int(length)))
print rand_str