docs: def init_app(self, app):
          """Flask application initialization.
  
          Initialize the Rate-Limiter, CORS and error handlers.
  
          :param app: An instance of :class:`flask.Flask`.
          """
          self.init_config(app)
  
          # Enable CORS support if desired
          if app.config['REST_ENABLE_CORS']:
              from flask_cors import CORS
              CORS(app)
              # CORS can be configured using CORS_* configuration variables.
  
          app.errorhandler(400)(create_api_errorhandler(
              status=400, message='Bad Request'))
          app.errorhandler(401)(create_api_errorhandler(
              status=401, message='Unauthorized'))
          app.errorhandler(403)(create_api_errorhandler(
              status=403, message='Forbidden'))
          app.errorhandler(404)(create_api_errorhandler(
              status=404, message='Not Found'))
          app.errorhandler(405)(create_api_errorhandler(
              status=405, message='Method Not Allowed'))
          app.errorhandler(406)(create_api_errorhandler(
              status=406, message='Not Acceptable'))
          app.errorhandler(409)(create_api_errorhandler(
              status=409, message='Conflict'))
          app.errorhandler(410)(create_api_errorhandler(
              status=410, message='Gone'))
          app.errorhandler(412)(create_api_errorhandler(
              status=412, message='Precondition Failed'))
          app.errorhandler(415)(create_api_errorhandler(
              status=415, message='Unsupported media type'))
          app.errorhandler(422)(create_api_errorhandler(
              status=422, message='Unprocessable Entity'))
          app.errorhandler(429)(create_api_errorhandler(
              status=429, message='Rate limit exceeded'))
          app.errorhandler(500)(create_api_errorhandler(
              status=500, message='Internal Server Error'))
          app.errorhandler(501)(create_api_errorhandler(
              status=501, message='Not Implemented'))
          app.errorhandler(502)(create_api_errorhandler(
              status=502, message='Bad Gateway'))
          app.errorhandler(503)(create_api_errorhandler(
              status=503, message='Service Unavailable'))
          app.errorhandler(504)(create_api_errorhandler(
              status=504, message='Gateway Timeout'))
  
          app.extensions['invenio-rest'] = self