[ndnSIM] Periodic stats of L3Tracer in a specific interface of a specific node

[Amin Karami]

Hi Alex,
There is an example as "ndn-simple-with-pit-count-stats" which prints 
periodic stats of PIT size in the nodes. 
(https://github.com/NDN-Routing/ndnSIM/blob/master/examples/ndn-simple-with-pit-count-stats.cc)
How does this periodic state work for L3Tracer statistics in a specific 
interface of a specific node? As i see in L3Tracer, there are 13 
statistic features in each second, where 11 features are for each 
interface in a node and 2 others for whole the node 
(OutSatisfiedInterests and OutTimedOutInterests).

Thank you in advance.

Best Regards,
Amin