| 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/codes | Package codes defines the canonical error codes used by gRPC. |
| google.golang.org/grpc/credentials/alts | Package alts implements the ALTS credential support by gRPC library, which encapsulates all the state needed by a client to authenticate with a server using ALTS and make various assertions, e.g., about the client's identity, role, or whether it is authorized to make a particular call. |
| google.golang.org/grpc/examples/features/proto/echo | |
| google.golang.org/grpc/status | Package status implements errors returned by gRPC. |
| log | Package log implements a simple logging package. |
| net | Package net provides a portable interface for network I/O, including TCP/IP, UDP, domain name resolution, and Unix domain sockets. |