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: main.go
    path of file: ./repos/gitkube/vendor/golang.org/x/tools/cmd/present
    
    the code of the file until where you have to start completion: // Copyright 2013 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"flag"
	"fmt"
	"go/build"
	"log"
	"net"
	"net/http"
	"net/url"
	"os"
	"strings"

	"golang.org/x/tools/present"
)

const basePkg = "golang.org/x/tools/cmd/present"

var (
	httpAddr      = flag.String("http", "127.0.0.1:3999", "HTTP service address (e.g., '127.0.0.1:3999')")
	originHost    = flag.String("orighost", "", "host component of web origin URL (e.g., 'localhost')")
	basePath      = flag.String("base", "", "base path for slide template and static resources")
	contentPath   = flag.String("content", ".", "base path for presentation content")
	usePlayground = flag.Bool("use_playground", false, "run code snippets using play.golang.org; if false, run them locally and deliver results by WebSocket transport")
	
    
func main() {
	flag.BoolVar(&present.PlayEnabled, "play", true, "enable playground (permit execution of arbitrary user code)")
	flag.BoolVar(&present.NotesEnabled, "notes", false, "enable presenter notes (press 'N' from the browser to display them)")
	flag.Parse()

	if os.Getenv("GAE_ENV") == "standard" {
		log.Print("Configuring for App Engine Standard")
		port := os.Getenv("PORT")
		if port == "" {
			port = "8080"
		}
		*httpAddr = fmt.Sprintf("0.0.0.0:%s", port)
		pwd, err := os.Getwd()
		if err != nil {
			log.Fatalf("Couldn't get pwd: %v\n", err)
		}
		*basePath = pwd
		*usePlayground = true
		*contentPath = "./content/"
	}

	if *basePath == "" {
		p, err := build.Default.Import(basePkg, "", build.FindOnly)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Couldn't find gopresent files: %v\n", err)
			fmt.Fprintf(os.Stderr, basePathMessage, basePkg)
			os.Exit(1)
		}
		*basePath = p.Dir
	}
	err := initTemplates(*basePath)
	if err != nil {
		log.Fatalf("Failed to parse templates: %v", err)
	}

	ln, err := net.Listen("tcp", *httpAddr)
	if err != nil {
		log.Fatal(err)
	}
	defer ln.Close()

	_, port, err := net.SplitHostPort(ln.Addr().String())
	if err != nil {
		log.Fatal(err)
	}

	origin := &url.URL{Scheme: "http"}
	if *originHost != "" {
		origin.Host = net.JoinHostPort(*originHost, port)
	} else if ln.Addr().(*net.TCPAddr).IP.IsUnspecified() {
		name, _ := os.Hostname()
		origin.Host = net.JoinHostPort(name, port)
	} else {
		reqHost, reqPort, err := net.SplitHostPort(*httpAddr)
		if err != nil {
			log.Fatal(err)
		}
		if reqPort == "0" {
			origin.Host = net.JoinHostPort(reqHost, port)
		} else {
			origin.Host = *httpAddr
		}
	}

	initPlayground(*basePath, origin)
	http.Handle("/static/", http.FileServer(http.Dir(*basePath)))

	if !ln.Addr().(*net.TCPAddr).IP.IsLoopback() &&
		present.PlayEnabled && !*nativeClient && !*usePlayground {
		log.Print(localhostWarning)
	}

	log.Printf("Open your web browser and visit %s", origin.String())
	if present.NotesEnabled {
		log.Println("Notes are enabled, press 'N' from the browser to display them.")
	}
	log.Fatal(http.Serve(ln, nil))
}