code: func (h *Client) ProductImpressionCategory(productImpressionCategory string) *Client {
  	h.productImpressionCategory = productImpressionCategory
  	h.productImpressionCategorySet = true
  	return h
  }
docs: // The category to which the product belongs. Impression List
  // index must be a positive integer between 1 and 200, inclusive.
  // Product index must be a positive integer between 1 and 200,
  // inclusive. For analytics.js the Enhanced Ecommerce plugin
  // must be installed before using this field.