code: func (ctx *Context) ServeFile(file string, names ...string) {
  	var name string
  	if len(names) > 0 {
  		name = names[0]
  	} else {
  		name = path.Base(file)
  	}
  	ctx.Resp.Header().Set("Content-Description", "File Transfer")
  	ctx.Resp.Header().Set("Content-Type", "application/octet-stream")
  	ctx.Resp.Header().Set("Content-Disposition", "attachment; filename="+name)
  	ctx.Resp.Header().Set("Content-Transfer-Encoding", "binary")
  	ctx.Resp.Header().Set("Expires", "0")
  	ctx.Resp.Header().Set("Cache-Control", "must-revalidate")
  	ctx.Resp.Header().Set("Pragma", "public")
  	http.ServeFile(ctx.Resp, ctx.Req.Request, file)
  }
docs: // ServeFile serves given file to response.