Adding slightly more complicated tutorial example
diff --git a/model/ccnx-content-store.cc b/model/ccnx-content-store.cc
index 881c881..f21841a 100644
--- a/model/ccnx-content-store.cc
+++ b/model/ccnx-content-store.cc
@@ -31,7 +31,7 @@
 namespace ns3
 {
 
-// NS_OBJECT_ENSURE_REGISTERED (CcnxContentStore);
+NS_OBJECT_ENSURE_REGISTERED (CcnxContentStore);
 
 using namespace __ccnx_private;