* REFERENCE FOR LATER: All GitHub PRs with 'cart' https://github.com/civicrm/civicrm-core/pulls?utf8=✓&q=is%3Apr+cart+
* REDUNDENT: All GitHub PRs with 'cart' https://github.com/civicrm/civicrm-core/pulls?utf8=✓&q=is%3Apr+cart+
* IGNORE THIS FOR ADDING: https://subscription.packtpub.com/book/web_development/9781782160441/8/ch08lvl1sec82/using-a-shopping-cart-and-drupal-views-for-event-registration
* IGNORE THIS FOR ADDING: https://subscription.packtpub.com/book/web_development/9781782160441/8/ch08lvl1sec82/using-a-shopping-cart-and-drupal-views-for-event-registration