但打字稿说：

[ts] Property ‘finally’ does not exist on type ‘Observable’.

import { AuthService } from './../../auth/auth.service';
import { Injectable } from '@angular/core';
import { Http,XHRBackend,RequestOptions,RequestOptionsArgs,Request,Response,Headers } from '@angular/http';

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/catch';
import 'rxjs/add/observable/throw';

@Injectable()
export class HttpService extends Http {

    constructor(
        backend: XHRBackend,options: RequestOptions,private authservice: AuthService
    ) {
        super(backend,options);
        this.updateHeaders(options.headers);
    }

    request(url: string|Request,options?: RequestOptionsArgs): Observable<Response> {
        return super.request(url,options)
            .catch((response: Response) => this.authError(response))
            .finally(() => {
                // ...
                /* Do something here when request is done. For example
                finish a spinning loader. */
            });
    }

    private authError(response: Response) {
        if (response.status === 401 || response.status === 403) {
            this.authservice.logout();
        }
        return Observable.throw(response);
    }

    private updateHeaders(headers: Headers) {
        headers.set('Content-Type','application/json');
        if (this.authservice.isloggedIn()) {
            headers.set('Authorization',`Bearer ${this.authservice.getToken()}`);
        }        
    }
}

如何在每个http请求之后运行一些代码？这样做的最佳方式是什么？