$ protoc --go_out=./protos --go_opt=paths=source_relative --go-grpc_out=./protos --go-grpc_opt=paths=source_relat
ive ./service.proto
https://grpc.io/docs/languages/go/quickstart/
https://github.com/grpc/grpc-go/tree/master/examples/helloworld
$ protoc --go_out=./protos --go_opt=paths=source_relative --go-grpc_out=./protos --go-grpc_opt=paths=source_relat
ive ./service.proto
https://grpc.io/docs/languages/go/quickstart/
https://github.com/grpc/grpc-go/tree/master/examples/helloworld