title: How can I simply return boolean with angular 6 .subscribe()
body: <p>New to Angular and I can't find anything to help me with this, would appreciate your help.</p>
  
  <p>Prefer to handle this situation without rxjs; ie. .pipe(map(...))</p>
  
  <p>The api responds with either: </p>
  
  <p>status(200) { token: "..." } --or-- status(400)</p>
  
  <pre><code>login(credentials) {
    return this.http.post('.../api/authenticate', credentials)
      .subscribe(
        response =&gt; {
          localStorage.setItem('token', response.token);
          return true;
        },
        () =&gt; {
          return false;
        });
  }
  </code></pre>
  
  <p>How does one simply return boolean?</p>