def attach_disk(disk_name, instance_name):
Displays usage of app based of flags and options
dataset/ETHPy150Open ClusterHQ/flocker/flocker/node/agents/gce.py/IGCEOperations.attach_disk--crossover with--dataset/ETHPy150Open kbknapp/Clapp-py/clapp/clapp.py/App._display_usage