@@ -541,7 +541,8 @@ def index():
541541 'corrections': list(result_container.corrections),
542542 'infoboxes': result_container.infoboxes,
543543 'suggestions': list(result_container.suggestions),
544− 'unresponsive_engines': list(result_container.unresponsive_engines)}),
544+ 'unresponsive_engines': list(result_container.unresponsive_engines)},
545+ default=lambda item: list(item) if isinstance(item, set) else item),
545546 mimetype='application/json')
546547 elif output_format == 'csv':
547548 csv = UnicodeWriter(StringIO())