code: def _validate_join(tensor_list_list):
      tensor_list_list = [
          indexed_slices.convert_n_to_tensor_or_indexed_slices(tl)
          for tl in tensor_list_list
      ]
      if not tensor_list_list:
          raise ValueError(
              "Expected at least one input in batch_join()."
          )
      return tensor_list_list
  
imports: from tensorflow.python.eager import context
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import indexed_slices
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import sparse_tensor
  from tensorflow.python.framework import tensor
  from tensorflow.python.framework import tensor_shape
  from tensorflow.python.layers import utils
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import control_flow_assert
  from tensorflow.python.ops import control_flow_ops
  from tensorflow.python.ops import data_flow_ops
  from tensorflow.python.ops import io_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import random_ops
  from tensorflow.python.ops import sparse_ops
  from tensorflow.python.ops import variable_v1
  from tensorflow.python.summary import summary
  from tensorflow.python.training import queue_runner
  from tensorflow.python.util import deprecation
  from tensorflow.python.util.compat import collections_abc
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 15 for calling a global function with example usage: _validate_join(tensor_list_list) and returns: tensor_list_list