Here are some sample subscriptions that can be used:
python ncc-establish-subscription.py --host=127.0.0.1 --port=2223 -u vagrant -p vagrant \
--period=1000 \
--xpath '/interfaces/interface[name="GigabitEthernet1"]/statistics/in-octets'
python ncc-establish-subscription.py --host=127.0.0.1 --port=2223 -u vagrant -p vagrant \
--period=1000 \
--xpath \
'/interfaces/interface[name="GigabitEthernet1"]/statistics/in-octets' \
'/interfaces/interface[name="GigabitEthernet1"]/statistics/out-octets'
python ncc-establish-subscription.py --host=127.0.0.1 --port=2223 -u vagrant -p vagrant \
--period=1000 \
--xpath '/memory-statistics'
python ncc-establish-subscription.py --host=127.0.0.1 --port=2223 -u vagrant -p vagrant \
--period=1000 \
--xpath '/memory-statistics/memory-statistic[name="Processor"]'
python ncc-establish-subscription.py --host=127.0.0.1 --port=2223 -u vagrant -p vagrant \
--period=1000 \
--xpath '/process-cpu-ios-xe-oper:cpu-usage/cpu-utilization/cpu-usage-processes/cpu-usage-process[pid=1][name="Chunk Manager"]'