title: How to get one product to modify information in the cart in Shopify?
body: <p>If a customer clicks a certain button in my Shopify store, I'd like to be able to add information to my cart using Liquid (or whatever is needed).  This information can be as simple as a string.  The customer won't see this information, but it will be used to modify the look of the cart page.  I can happily parse it/handle it as a string, if that's my only option, but so far I can't get any information to be sent.  I have tried modifying cart.note using a <code>{% capture %}</code> block, but that never ended up modifying anything permanently.  I also am not sure how to change <code>line_item</code> properties, but that might do it as well.</p>