AI solution for TypeScript puzzle on BFE.dev
20: implement IsNever<T>

type IsNever<T> = [T] extends [never] ? true : false;

In the above code, we define a generic type IsNever<T> that checks if the input type T is of type never. We do this by creating a conditional type that checks if T is assignable to never. If the result is true, then we return true. Otherwise, we return false. We use the square bracket syntax to force the compiler to perform a distributive conditional type.