anchor.diff:          body: {"username" : username,
                  "password" : password}).then((response) {
         checkResponse(response, 201);
  -      return _token = JSON.decode(response.body)["api_token"];
  +      return token = JSON.decode(response.body)["api_token"];
       });
     }
     
  
positive.code: 
  class DuseClient {
    final RestClient client;
    String _token;
    KeyPair _private;
    
    DuseClient(Uri baseUri, ClientFactory clientFactory)
        : client = initializeClient(baseUri, clientFactory);
    
    Map<String, String> get authorizationHeader =>
        {"authorization": _token};
    
    static RestClient initializeClient(Uri baseUri,
                                       ClientFactory clientFactory) {
  
negative.code:     return client.slash("users").all(headers: authorizationHeader);
    }
    
    bool get isLoggedIn => null != token;
    bool get hasPrivateKey => null != _private;
    
    void checkLoggedIn() {
  