code: public ZapReply nextReply(boolean wait)
      {
          if (!repliesEnabled) {
              System.out.println("ZAuth: replies are disabled. Please use replies(true);");
              return null;
          }
          return ZapReply.recv(replies, wait);
      }
docs: Retrieves the next ZAP reply.
  @param wait true to wait for the next reply, false to immediately return if there is no next reply.
  @return the next reply or null if the actor is closed or if there is no next reply yet.