title: Getting error while trying to use paramMap for getting route parameters
body: <pre><code>export class HeroDetailComponent {
      heroes;
      constructor(private route: ActivatedRoute, private router: Router, private hs : HeroService){
      }
      ngOnInit(){
          this.route.paramMap
              .switchMap((params : ParamMap) =&gt; 
                  this.hs.getHeroes(params.get('id')))
              .subscribe((heroes) =&gt; {
                  console.log("checking for heroes n subscribe",heroes);
                  this.heroes = heroes})          
      }
  
  }
  </code></pre>
  
  <p>Getting following error </p>
  
  <p>paramMap doesn't exist on type 'ActivatedRoute'</p>