code: function submitFreeTransaction( partialCart, onComplete ) {
  	const cart = fillInAllCartItemAttributes( partialCart, productsList.get() ),
  		transaction = {
  			payment: fullCreditsPayment,
  		};
  
  	submitTransaction( { cart, transaction }, onComplete );
  }
docs: /*
  Submit a free cart transaction
  
  This an helper method to be used for when we want to make a
  quick (free) transaction without a valid payment method.
  The default payment method for free carts is used here.
  
  {cart} [partialCart] - A cart-like object. We just need a valid `product_slug` property for cart items
  {function} [onComplete] Callback function called on completion