sku constant
sku [Expects: http://schema.org/Text]
The Stock Keeping Unit (SKU), i.e. a merchant-specific identifier for a product or service, or the product to which the offer refers.
Can be used on: http://schema.org/Demand, http://schema.org/Offer, http://schema.org/Product
Implementation
static const sku = IriTerm.prevalidated('http://schema.org/sku');