Serve a 1-pixel PNG in Go

pixel.go

// Package pixel serves a one pixel image.
package pixel

import (
        "encoding/base64"
        "net/http"
)

const px = `iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR4nGP6zwAAAgcBApocMXEAAAAASUVORK5CYII=`

func init() {
        b, _ := base64.StdEncoding.DecodeString(px)
        http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
                w.Header().Set("Content-Type", "image/png")
                w.Write(b)
        })
}

This is for App Engine. To run on Heroku, change init() to main().