What is the best way to create a schema with a self referencing type? For example, say I have a "category" type that can have 0:M subcategories. I could create several different types (one for each potential level) or the category type could reference itself with a "ParentType" field. As I am new to graphql and the Apollo client, I am sure there are considerations not just for the storage/schema but also for data retrieval and writes. Was hoping that the experts could provide some experiential best practices.