code: def _train_input_fn():
      """Fake input function that returns a static number of list of pairs."""
      # batch_size = 2, list_size = 3.
      features = {
          # Context features with shape [2, 1]
          "context": tf.constant([[178.0], [155.0]]),
          # Listwise weight with shape [2, 1]
          "weight": tf.constant([[1.0], [1.0]]),
          # Example features with shape [2, 3, 1] for 3 examples.
          "age": tf.constant(
              [[[10.0], [20.0], [20.0]], [[50.0], [30.0], [30.0]]]
          ),
      }
      # Label with shape [2, 3].
      label = tf.constant([[1.0, 0.0, 0.0], [1.0, 0.0, 0.0]])
      return features, label
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  from absl.testing import parameterized
  import tensorflow
  from tensorflow import estimator
  from tensorflow_ranking.python import feature
  from tensorflow_ranking.python import head
  from tensorflow_ranking.python import losses
  from tensorflow_ranking.python import model
label_desc: Use image node_id 3 for calling a global function with example usage: _train_input_fn() and returns: features,  label