Easy Password Generator - Python

import random
import string
import sys

def generate_passwd_with_len(pass_len):
    mas = string.printable[:-7]
    pas = ''
    for i in range(pass_len):
        pas += random.choice(mas)
    return pas

if __name__ == '__main__':
    if (len(sys.argv) == 1):
        print generate_passwd_with_len(11)
    else:
        pas_len = sys.argv[1]
        if ( pas_len.isdigit() ):
            print generate_passwd_with_len( int(pas_len) )
        else:
            print "Error! Enter passwd lenght!"