diff --git a/colab/plugins/utils/signals.py b/colab/plugins/utils/signals.py
index b1cd4b5..212ec9f 100644
--- a/colab/plugins/utils/signals.py
+++ b/colab/plugins/utils/signals.py
@@ -1,8 +1,13 @@
+
+from abc import abstractmethod
+
+
 class AbstractSignal():
 
+    @abstractmethod
     def register_signal(self):
-        raise(Exception, 'NOT IMPLEMENTED')
-
+        raise NotImplementedError
 
+    @abstractmethod
     def connect_signal(self):
-        raise(Exception, 'NOT IMPLEMENTED')
+        raise NotImplementedError
--
libgit2 0.21.2