def l13(res, req, resp):
    return "HTTP_IF_MODIFIED_SINCE" in req.META
Valid the format of port.
dataset/ETHPy150Open benoitc/dj-webmachine/webmachine/decisions.py/l13--crossover with--dataset/ETHPy150Open openstack/compass-core/compass/db/validator.py/is_valid_port