code: def mock_loss_fn(onehot_labels, logits):
      """Mock loss_fn that returns MSE loss."""
      return tf.keras.losses.mean_squared_error(onehot_labels, logits)
  
file_path: neural-structured-learning/neural_structured_learning/lib/regularizer_test.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import neural_structured_learning.configs
  from neural_structured_learning.lib import regularizer
  import numpy
  import tensorflow
label_desc: Use image node_id 2 for calling a global function with example usage: mock_loss_fn(onehot_labels, logits) and returns: tf