If not None, a TPUEmbeddingConfiguration proto
describing the desired configuration of the hardware embedding lookup
tables. If embedding_config is None, no hardware embeddings can be used.
The job (the XXX in TensorFlow device specification /job:XXX) that
contains the TPU devices that will be initialized. If job=None it is
assumed there is only one job in the TensorFlow flock, and an error will
be returned if this assumption does not hold.
Set the configuration whether
we want to close TPU chips when there is a compilation failure.
A serialized TopologyProto that describes the TPU system. Note:
the topology must be evaluated using Session.run before it can be used.