Parameters: import_name – the name of the application package static_url_path – can be used to specify a different path for the static files on the web. Defaults to the name of the static_folder folder. static_folder – the folder with static files that should be served at static_url_path. Defaults to the 'static' folder in the root path of the application. template_folder – the folder that contains the templates that should be used by the application. Defaults to 'templates' folder in the root path of the application. instance_path – An alternative instance path for the application. By default the folder 'instance' next to the package or module is assumed to be the instance path. instance_relative_config – if set to True relative filenames for loading the config are assumed to be relative to the instance path instead of the application root. root_path – Flask by default will automatically calculate the path to the root of the application. In certain situations this cannot be achieved (for instance if the package is a Python 3 namespace package) and needs to be manually defined.