code: def __call__(self, **kwargs):
      return self.predictive_distribution.mean(**kwargs)
  
file_path: probability/tensorflow_probability/python/experimental/bayesopt/acquisition/acquisition_function_test.py
imports: from absl.testing import parameterized
  import numpy
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import normal
  from tensorflow_probability.python.experimental.bayesopt.acquisition import acquisition_function
  from tensorflow_probability.python.internal import test_util
label_desc: Use image node_id 2 for calling the TestFunction obj's underlying member method code with example usage: obj.__call__() and returns: self