how to use http://martini.codegangsta.io/ with google app engine

hello.go

package hello

import (
  "net/http"

  "github.com/codegangsta/martini"
)

func init() {
  m := martini.Classic()

  m.Get("/", func() string {
    return "Martini on app engine!"
  })

  http.Handle("/", m)
}