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: gen.go
    path of file: ./repos/go-starter-kit/vendor/golang.org/x/text/encoding/htmlindex
    
    the code of the file until where you have to start completion: // Copyright 2015 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.

// +build ignore

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log"
	"strings"

	"golang.org/x/text/internal/gen"
)

type group struct {
	Encodings []struct {
		Labels []string
		Name   string
	}
}

func main() {
	gen.Init()

	r := gen.Open("http://www.w3.org/TR", "w3", "encoding/indexes/encodings.json")
	var groups []group
	if err := json.NewDecoder(r).Decode(&groups); err != nil {
		log.Fatalf("Error reading encodings.json: %v", err)
	}

	w := &bytes.Buffer{}
	fmt.Fprintln(w, "type htmlEncoding byte")
	fmt.Fprintln(w, "const (")
	for i, g := range groups {
		for _, e := range g.Encodings {
			name := consts[e.Name]
			if name == "" {
				log.Fatalf("No const defined for %s.", e.Name)
			}
			if i == 0 {
				fmt.Fprintf(w, "%s htmlEncoding = iota\n", name)
			} else {
				fmt.Fprintf(w, "%s\n", name)
			}
		}
	}
	fmt.Fprintln(w, "numEncodings")
	fmt.Fprint(w, ")\n\n")

	fmt.Fprintln(w, "var canonical = [numEncodings]string{"
    
func main() {
	gen.Init()

	r := gen.Open("http://www.w3.org/TR", "w3", "encoding/indexes/encodings.json")
	var groups []group
	if err := json.NewDecoder(r).Decode(&groups); err != nil {
		log.Fatalf("Error reading encodings.json: %v", err)
	}

	w := &bytes.Buffer{}
	fmt.Fprintln(w, "type htmlEncoding byte")
	fmt.Fprintln(w, "const (")
	for i, g := range groups {
		for _, e := range g.Encodings {
			name := consts[e.Name]
			if name == "" {
				log.Fatalf("No const defined for %s.", e.Name)
			}
			if i == 0 {
				fmt.Fprintf(w, "%s htmlEncoding = iota\n", name)
			} else {
				fmt.Fprintf(w, "%s\n", name)
			}
		}
	}
	fmt.Fprintln(w, "numEncodings")
	fmt.Fprint(w, ")\n\n")

	fmt.Fprintln(w, "var canonical = [numEncodings]string{")
	for _, g := range groups {
		for _, e := range g.Encodings {
			fmt.Fprintf(w, "%q,\n", e.Name)
		}
	}
	fmt.Fprint(w, "}\n\n")

	fmt.Fprintln(w, "var nameMap = map[string]htmlEncoding{")
	for _, g := range groups {
		for _, e := range g.Encodings {
			for _, l := range e.Labels {
				fmt.Fprintf(w, "%q: %s,\n", l, consts[e.Name])
			}
		}
	}
	fmt.Fprint(w, "}\n\n")

	var tags []string
	fmt.Fprintln(w, "var localeMap = []htmlEncoding{")
	for _, loc := range locales {
		tags = append(tags, loc.tag)
		fmt.Fprintf(w, "%s, // %s \n", consts[loc.name], loc.tag)
	}
	fmt.Fprint(w, "}\n\n")

	fmt.Fprintf(w, "const locales = %q\n", strings.Join(tags, " "))

	gen.WriteGoFile("tables.go", "htmlindex", w.Bytes())
}