Traceback (most recent call last):
  File "src/train.py", line 144, in <module>
    tf.estimator.train_and_evaluate(estimator, train_spec, eval_spec)
  File "/home/nnayak/.local/lib/python3.6/site-packages/tensorflow/python/estimator/training.py", line 451, in train_and_evaluate
    return executor.run()
  File "/home/nnayak/.local/lib/python3.6/site-packages/tensorflow/python/estimator/training.py", line 590, in run
    return self.run_local()
  File "/home/nnayak/.local/lib/python3.6/site-packages/tensorflow/python/estimator/training.py", line 691, in run_local
    saving_listeners=saving_listeners)
  File "/home/nnayak/.local/lib/python3.6/site-packages/tensorflow/python/estimator/estimator.py", line 376, in train
    loss = self._train_model(input_fn, hooks, saving_listeners)
  File "/home/nnayak/.local/lib/python3.6/site-packages/tensorflow/python/estimator/estimator.py", line 1145, in _train_model
    return self._train_model_default(input_fn, hooks, saving_listeners)
  File "/home/nnayak/.local/lib/python3.6/site-packages/tensorflow/python/estimator/estimator.py", line 1170, in _train_model_default
    features, labels, model_fn_lib.ModeKeys.TRAIN, self.config)
  File "/home/nnayak/.local/lib/python3.6/site-packages/tensorflow/python/estimator/estimator.py", line 1133, in _call_model_fn
    model_fn_results = self._model_fn(features=features, **kwargs)
  File "/home/nnayak/LISA/src/model.py", line 195, in model_fn
    initializer=tf.constant_initializer(task_transition_stats),
  File "/home/nnayak/.local/lib/python3.6/site-packages/tensorflow/python/ops/init_ops.py", line 207, in __init__
    "tuple of values, or numpy.ndarray)." % type(value))
TypeError: Invalid type for initial value: <class 'NoneType'> (expected Python scalar, list or tuple of values, or numpy.ndarray).