title: Cannot find module 'rxjs/internal/Observable'
body: <p>I want to use JwtHelperService module in my service but I got below error:</p>
  
  <pre><code>ERROR in node_modules/@auth0/angular-jwt/src/jwt.interceptor.d.ts(3,28): error TS2307: Cannot find module 'rxjs/internal/Observable'.
  </code></pre>
  
  <p>I have isAuthenticated function in my service.</p>
  
  <pre><code>import { JwtHelperService } from '@auth0/angular-jwt';
  import * as jwt_decode from 'jwt-decode';
  
  @Injectable()
  export class MembershipService{
      constructor(private http: Http,
         private mainService: MainService,
         public jwtHelper: JwtHelperService){}
  
      public isAuthenticated(): boolean {
          const token = localStorage.getItem('loggedToken');
          // Check whether the token is expired and return
          // true or false
          return !this.jwtHelper.isTokenExpired(token);
  
      }
  }
  </code></pre>
  
  <p>Also my angular version is 5.0 </p>
  
  <p>I appreciate any help</p>