Examples: incorporate latest change of NDNPing Class

Change-Id: I01d59de621992a87c082074766dc18e9a7b549a2
diff --git a/examples/nlsr/mcn_failure.py b/examples/nlsr/mcn_failure.py
index 1bd0449..decb586 100644
--- a/examples/nlsr/mcn_failure.py
+++ b/examples/nlsr/mcn_failure.py
@@ -1,6 +1,6 @@
 # -*- Mode:python; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
 #
-# Copyright (C) 2015-2019, The University of Memphis,
+# Copyright (C) 2015-2021, The University of Memphis,
 #                          Arizona Board of Regents,
 #                          Regents of the University of California.
 #
@@ -32,7 +32,7 @@
 from minindn.apps.nlsr import Nlsr
 from minindn.helpers.experiment import Experiment
 from minindn.helpers.nfdc import Nfdc
-from minindn.helpers.ndnpingclient import NDNPingClient
+from minindn.helpers.ndnping import NDNPing
 
 from nlsr_common import getParser
 
@@ -63,7 +63,7 @@
     if args.nPings != 0:
         Experiment.setupPing([mcn], Nfdc.STRATEGY_BEST_ROUTE)
         for nodeToPing in pingedDict[mcn]:
-            NDNPingClient.ping(mcn, nodeToPing, PING_COLLECTION_TIME_AFTER_RECOVERY)
+            NDNPing.ping(mcn, nodeToPing, nPings=PING_COLLECTION_TIME_AFTER_RECOVERY)
 
         time.sleep(PING_COLLECTION_TIME_AFTER_RECOVERY)