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/gccrs/libgo/go/image/color/palette
    
    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.

//go:build ignore

package main

// This program generates palette.go. Invoke it as
//	go run gen.go -output palette.go

import (
	"bytes"
	"flag"
	"fmt"
	"go/format"
	"io"
    
func printPlan9(w io.Writer) {
	c, lines := [3]int{}, [256]string{}
	for r, i := 0, 0; r != 4; r++ {
		for v := 0; v != 4; v, i = v+1, i+16 {
			for g, j := 0, v-r; g != 4; g++ {
				for b := 0; b != 4; b, j = b+1, j+1 {
					den := r
					if g > den {
						den = g
					}
					if b > den {
						den = b
					}
					if den == 0 {
						c[0] = 0x11 * v
						c[1] = 0x11 * v
						c[2] = 0x11 * v
					} else {
						num := 17 * (4*den + v)
						c[0] = r * num / den
						c[1] = g * num / den
						c[2] = b * num / den
					}
					lines[i+(j&0x0f)] =
						fmt.Sprintf("\tcolor.RGBA{0x%02x, 0x%02x, 0x%02x, 0xff},", c[0], c[1], c[2])
				}
			}
		}
	}
	fmt.Fprintln(w, "// Plan9 is a 256-color palette that partitions the 24-bit RGB space")
	fmt.Fprintln(w, "// into 4×4×4 subdivision, with 4 shades in each subcube. Compared to the")
	fmt.Fprintln(w, "// WebSafe, the idea is to reduce the color resolution by dicing the")
	fmt.Fprintln(w, "// color cube into fewer cells, and to use the extra space to increase the")
	fmt.Fprintln(w, "// intensity resolution. This results in 16 gray shades (4 gray subcubes with")
	fmt.Fprintln(w, "// 4 samples in each), 13 shades of each primary and secondary color (3")
	fmt.Fprintln(w, "// subcubes with 4 samples plus black) and a reasonable selection of colors")
	fmt.Fprintln(w, "// covering the rest of the color cube. The advantage is better representation")
	fmt.Fprintln(w, "// of continuous tones.")
	fmt.Fprintln(w, "//")
	fmt.Fprintln(w, "// This palette was used in the Plan 9 Operating System, described at")
	fmt.Fprintln(w, "// https://9p.io/magic/man2html/6/color")
	fmt.Fprintln(w, "var Plan9 = []color.Color{")
	for _, line := range lines {
		fmt.Fprintln(w, line)
	}
	fmt.Fprintln(w, "}")
	fmt.Fprintln(w)
}