What does the `-?` modifier do in a mapped type like `{ [K in keyof T]-?: T[K] }`? TypeScript ProfessionalHard Try Now
What does `type ReturnType = T extends (…args: any[]) => infer R ? R : never` do? TypeScript ProfessionalHard Try Now
What is the output of `type Flatten = T extends Array ? U : T` when applied as `Flatten`? TypeScript ProfessionalHard Try Now
Which of the following correctly describes a distributive conditional type? TypeScript ProfessionalHard Try Now
