| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| google.golang.org/grpc | Package grpc implements an RPC system called gRPC. |
| google.golang.org/grpc/examples/features/proto/echo | |
| google.golang.org/grpc/examples/helloworld/helloworld | |
| log | Package log implements a simple logging package. |
| time | Package time provides functionality for measuring and displaying time. |