You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: testserver.go
    path of file: ./repos/grpcurl/internal/testing/cmd/testserver
    
    the code of the file until where you have to start completion: // Command testserver spins up a test GRPC server.
package main

import (
	"context"
	"flag"
	"fmt"
	"net"
	"os"
	"sync/atomic"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/grpclog"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/reflection"
	"google.golang.org/grpc/status"

	"github.com/fullstorydev
    
func unaryLogger(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
	i := atomic.AddInt32(&id, 1) - 1
	grpclog.Infof("start <%d>: %s\n", i, info.FullMethod)
	start := time.Now()
	rsp, err := handler(ctx, req)
	var code codes.Code
	if stat, ok := status.FromError(err); ok {
		code = stat.Code()
	} else {
		code = codes.Unknown
	}
	grpclog.Infof("completed <%d>: %v (%d) %v\n", i, code, code, time.Since(start))
	return rsp, err
}