| 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/health | Package health provides a service that exposes server's health and it must be imported to enable support for client-side health checks. |
| google.golang.org/grpc/resolver | Package resolver defines APIs for name resolution in gRPC. |
| google.golang.org/grpc/resolver/manual | Package manual defines a resolver that can be used to manually send resolved addresses to ClientConn. |
| log | Package log implements a simple logging package. |
| time | Package time provides functionality for measuring and displaying time. |