code: func (h *Client) ProductAction(productAction string) *Client {
  	h.productAction = productAction
  	h.productActionSet = true
  	return h
  }
docs: // The role of the products included in a hit. If a product
  // action is not specified, all product definitions included
  // with the hit will be ignored. Must be one of: detail, click,
  // add, remove, checkout, checkout_option, purchase, refund.
  // For analytics.js the Enhanced Ecommerce plugin must be installed
  // before using this field.