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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fn_device_dependency_dict():
 """State container for fn_device_dependency."""

  default_graph = tf.get_default_graph()
  if not hasattr(default_graph, "dependency_dict"):
    default_graph.dependency_dict = collections.defaultdict(list)
  return default_graph.dependency_dict