code: func NewInbox() string {
  	var b [inboxPrefixLen + nuidSize]byte
  	pres := b[:inboxPrefixLen]
  	copy(pres, InboxPrefix)
  	ns := b[inboxPrefixLen:]
  	copy(ns, nuid.Next())
  	return string(b[:])
  }
docs: // NewInbox will return an inbox string which can be used for directed replies from
  // subscribers. These are guaranteed to be unique, but can be shared and subscribed
  // to by others.