docs: private void quit(String command, Socket socket) throws IOException {
          lock.lock();
          try {
              if (!envState.done)
                  envState.quit = true;
              DataOutputStream dout = new DataOutputStream(socket.getOutputStream());
              dout.writeInt(BYTES_INT);
              dout.writeInt(envState.done ? 1 : 0);
              dout.flush();
          } finally {
              lock.unlock();
          }
      }