class_docstr: Modifies the graph by adding a variable.
class_docstr_tok: ["Modifies","the","graph","by","adding","a","variable","."]
docstr: Adds a variable to the graph.
  
  Args:
    session: A `tf.Session` object that can be used to run ops.
  
  Raises:
    ValueError: If we've not begun a run.
code: def end(self, session):
      """Adds a variable to the graph.
  
      Args:
        session: A `tf.Session` object that can be used to run ops.
  
      Raises:
        ValueError: If we've not begun a run.
      """
  
      _ = session
      if not self._begun:
          raise ValueError("end called without begin.")
      self._begun = False
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import shutil
  import struct
  import sys
  from absl import flags
  from absl.testing import parameterized
  from adanet import ensemble
  from adanet import subnetwork
  from adanet import tf_compat
  from adanet.core.architecture import _Architecture
  from adanet.core.candidate import _Candidate
  from adanet.core.ensemble_builder import _EnsembleSpec
  from adanet.core.ensemble_builder import _SubnetworkSpec
  from adanet.core.eval_metrics import _EnsembleMetrics
  from adanet.core.eval_metrics import _IterationMetrics
  from adanet.core.eval_metrics import _SubnetworkMetrics
  import tensorflow.compat.v2
label_desc: Use image node_id 3 for calling the ModifierSessionRunHook obj's underlying member method code with example usage: obj.end(session) without return types