diff --git a/navipy/moving/agent.py b/navipy/moving/agent.py
index bb50b4dc92765a9015ac4f4e426c2456edab6a81..3a13cc2eb3dac580baa1c90ff26bcb667a34ba9a 100644
--- a/navipy/moving/agent.py
+++ b/navipy/moving/agent.py
@@ -12,6 +12,7 @@ import navipy.moving.maths as navimomath
 
 
 def defaultcallback(*args, **kwargs):
+    """default call back"""
     raise NameError('No Callback')