Assert that a type is not branded

Question

If we define a type brand, for example:

declare const nominalSymbol: unique symbol;
type Nominal<T extends string, U> = U & { [nominalSymbol]: T };

Is there a way to define a type NotNominal that resolves to U< if U is not a brand type /code>.

declare const nominalSymbol: unique symbol;
type Nominal<T extends string, U> = U & { [nominalSymbol]: T };

type BrandedType = Nominal<'Address', string>;

type a = NotNominal<string> // This should be `string`
type b = NotNominal<Address> // This should be `never`

Answer 1

type NotNominal<U> = U extends { [nominalSymbol]: string } ? never : U