| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| google.golang.org/grpc/credentials | Package credentials implements various credentials supported by gRPC library, which encapsulate all the state needed by a client to authenticate with a server and make various assertions, e.g., about the client's identity, role, or whether it is authorized to make a particular call. |
| net | Package net provides a portable interface for network I/O, including TCP/IP, UDP, domain name resolution, and Unix domain sockets. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |