code: def flatten(list_of_lists):
      """Flatten one level of nesting."""
      return itertools.chain.from_iterable(list_of_lists)
  
file_path: tensorflow-upstream/tensorflow/python/kernel_tests/nn_ops/ctc_decoder_ops_test.py
imports: import itertools
  import numpy
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops_stack
  from tensorflow.python.ops import ctc_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 2 for calling a global function with example usage: flatten(list_of_lists) and returns: itertools