undefined method in CI cart library options

[eluser]umefarooq[/eluser]
Hi i creating a simple cart using CI library and try to access some options of item using as per user guide

Code:

$this->cart->options(rowid);

this function is missing in CI cart library i have check in CI 1.7.2 and also CI 2 in both codes this function is missing

Call to undefined method CI_Cart::options()