def check_app_config_brackets(self):
        """Check for App config with extraneous brackets in section names."""
        for sn, app in cherrypy.tree.apps.items():
            if not isinstance(app, cherrypy.Application):
                continue
            if not app.config:
                continue
            for key in app.config.keys():
                if key.startswith('[') or key.endswith(']'):
                    warnings.warn(
                        'The application mounted at %r has config '
                        'section names with extraneous brackets: %r. '
                        'Config *files* need brackets; config *dicts* '
                        '(e.g. passed to tree.mount) do not.' % (sn, key),
                    )
Check for App config with extraneous brackets in section names.
cherrypy/_cpchecker.py