code: def init_app(self, app, **kwargs):
          
          # Init the configuration
          self.init_config(app)
          # Enable Rate limiter
          self.limiter = Limiter(app, key_func=get_ipaddr)
          # Enable secure HTTP headers
          if app.config['APP_ENABLE_SECURE_HEADERS']:
              self.talisman = Talisman(
                  app, **app.config.get('APP_DEFAULT_SECURE_HEADERS', {})
              )
          # Enable PING view
          if app.config['APP_HEALTH_BLUEPRINT_ENABLED']:
              blueprint = Blueprint('invenio_app_ping', __name__)
  
              @blueprint.route('/ping')
              def ping():
                  """Load balancer ping view."""
                  return 'OK'
  
              ping.talisman_view_options = {'force_https': False}
  
              app.register_blueprint(blueprint)
  
          requestid_header = app.config.get('APP_REQUESTID_HEADER')
          if requestid_header:
              @app.before_request
              def set_request_id():
                  """Extracts a request id from an HTTP header."""
                  request_id = request.headers.get(requestid_header)
                  if request_id:
                      # Capped at 200 to protect against malicious clients
                      # sending very large headers.
                      g.request_id = request_id[:200]
  
          # If installed register the Flask-DebugToolbar extension
          try:
              from flask_debugtoolbar import DebugToolbarExtension
              app.extensions['flask-debugtoolbar'] = DebugToolbarExtension(app)
          except ImportError:
              app.logger.debug('Flask-DebugToolbar extension not installed.')
  
          # Register self
          app.extensions['invenio-app'] = self
docs: Initialize application object.
  
          :param app: An instance of :class:`~flask.Flask`.