diff --git a/weboob/capabilities/calendar.py b/weboob/capabilities/calendar.py
index c6398134..46336982 100644
--- a/weboob/capabilities/calendar.py
+++ b/weboob/capabilities/calendar.py
@@ -154,3 +154,4 @@ class ICapCalendarEvent(IBaseCap):
         :param is_attending : is attending to the event or not
         :type is_attending : bool
         """
+        raise NotImplementedError()