code: def authenticate(self):
          
          if request.headers.get('Authorization') or request.args.get('access_token'):
              realm = 'Bearer realm="%s", error="invalid_token"' % __package__
          else:
              realm = 'Bearer realm="%s"' % __package__
          resp = Response(None, 401, {'WWW-Authenticate': realm})
          abort(401, description='Please provide proper credentials', response=resp)
docs: Indicate to the client that it needs to authenticate via a 401.