Usage
"subset"(x, sku = NULL, developer = NULL, title = NULL, version = NULL, version.lte = NULL, version.gte = NULL, product.type.identifier = NULL, units = NULL, units.lte = NULL, units.gte = NULL, developer.proceeds = NULL, developer.proceeds.lte = NULL, developer.proceeds.gte = NULL, date = NULL, date.lte = NULL, date.gte = NULL, customer.currency = NULL, country.code = NULL, currency.of.proceeds = NULL, apple.identifier = NULL, customer.price = NULL, promo.code = NULL, parent.identifier = NULL, subscription = NULL, period = NULL, ...)