docs: private void peek(String command, Socket socket, DataInputStream din) throws IOException {
  
          DataOutputStream dout = new DataOutputStream(socket.getOutputStream());
          byte[] obs;
          boolean done;
  
          lock.lock();
          try {
              obs = getObservation(false);
              done = envState.done;
          } finally {
              lock.unlock();
          }
  
          dout.writeInt(obs.length);
          dout.write(obs);
  
          dout.writeInt(1);
          dout.writeByte(done ? 1 : 0);
  
          dout.flush();
      }