code: def _log_prob(self, value):
      err = value - self.a * tf.pad(value[:-1], [[1, 0]], "CONSTANT")
      lpdf = self.shocks._log_prob(err)
      return tf.reduce_sum(lpdf)
  
file_path: edward/tests/inferences/ar_process_test.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import edward
  import numpy
  import tensorflow
  from edward.models import Normal, PointMass
  from scipy.optimize import minimize
  from edward.models import RandomVariable
  from tensorflow.contrib.distributions import Distribution
  from tensorflow.contrib.distributions import FULLY_REPARAMETERIZED
label_desc: Use image node_id 2 for calling the AutoRegressive obj's underlying member method code with example usage: obj._log_prob(value) and returns: tf