code: def _loss_fn(self, val0, val1):
      return 0.5 * tf.reduce_sum(
          input_tensor=tf.math.squared_difference(val0, val1), axis=1
      )
  
file_path: privacy/tensorflow_privacy/privacy/optimizers/dp_optimizer_eager_test.py
imports: from absl.testing import parameterized
  import numpy
  import tensorflow
  from tensorflow_privacy.privacy.dp_query import gaussian_query
  from tensorflow_privacy.privacy.optimizers import dp_optimizer
label_desc: Use image node_id 2 for calling the DPOptimizerEagerTest obj's underlying member method code with example usage: obj._loss_fn(val0, val1) and returns: unknown