Imports of nats-sub command

PathSynopsis
flagPackage flag implements command-line flag parsing.
github.com/nats-io/go-natsA Go client for the NATS messaging system (https://nats.io).
logPackage log implements a simple logging package.
runtimePackage runtime contains operations that interact with Go's runtime system, such as functions to control goroutines.
timePackage time provides functionality for measuring and displaying time.