Method declared inside interface seems redundant

[cirossmonteiro]

The method unsubscribe(): void in second interface seems redundant, since it extends an interface where it's already declared the same way.

export interface Unsubscribable {
  unsubscribe(): void;
}
...
export interface SubscriptionLike extends Unsubscribable {
    unsubscribe(): void;
    readonly closed: boolean;
}

Source code