code: def inputs(self):
      return [
          tf.TensorSpec((None, SEQ_LEN), tf.int32, "input"),
          tf.TensorSpec((None, SEQ_LEN), tf.int32, "nextinput"),
      ]
  
file_path: tensorpack/examples/PennTreebank/PTB-LSTM.py
imports: import argparse
  import numpy
  import os
  import tensorflow
  from tensorpack import *
  from tensorpack.tfutils import gradproc, optimizer, summary
  from tensorpack.utils import logger
  from tensorpack.utils.argtools import memoized_ignoreargs
  from tensorpack.utils.fs import download, get_dataset_path
  import reader
  from reader import ptb_producer
label_desc: Use image node_id 1 for calling the Model obj's underlying member method code with example usage: obj.inputs() and returns: list