code: func (pr *publishRequest) serveZip() {
  	filename := ""
  	if len(pr.subres) > len("/=z/") {
  		filename = pr.subres[4:]
  	}
  	zh := &zipHandler{
  		fetcher:  pr.ph.cl,
  		cl:       pr.ph.cl,
  		root:     pr.subject,
  		filename: filename,
  	}
  	zh.ServeHTTP(pr.rw, pr.req)
  }
docs: // serveZip streams a zip archive of all the files "under"
  // pr.subject. That is, all the files pointed by file permanodes,
  // which are directly members of pr.subject or recursively down
  // directory permanodes and permanodes members.