Imports of client command

PathSynopsis
contextPackage context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
flagPackage flag implements command-line flag parsing.
google.golang.org/grpc
google.golang.org/grpc/credentials/alts
google.golang.org/grpc/grpclog
google.golang.org/grpc/interop/grpc_testing
timePackage time provides functionality for measuring and displaying time.