getPage(page: number, args?: Object): Observable<IPaginatableResult> {
    let params = new HttpParams();
    const url = this.whichUrl(page);
    const t = new Date();
    for (let arg in args) {
      params = params.set(arg, args[arg]);
    }
    params = params.set('timestamp', t.toDateString());
    return this.http
      .get(url, {
        params: params
      })
      .switchMap(res => {
        let ret = res as IPaginatableResult;
        ret.list.map(val => Object.assign(this.typeObj(), <T>val));
        return Observable.of(ret);
      });
  }