TS Type Inference 3

library.ts

export type Url = string;
export interface HttpResponse<T> {
    data: T;
}
export type PromisedHttpResponse<T> = Promise<HttpResponse<T>>;
export class HttpService<T> {
    save(url: Url, data: T): PromisedHttpResponse<T> {
        return Promise.resolve({data});
    };
}