code: func (h *Client) ProductImpressionCustomDimension(productImpressionCustomDimension string) *Client {
  	h.productImpressionCustomDimension = productImpressionCustomDimension
  	h.productImpressionCustomDimensionSet = true
  	return h
  }
docs: // A product-level custom dimension where dimension index is
  // a positive integer between 1 and 200, inclusive. 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.