This function wraps tensor placeholders in a supervised_receiver_fn
with the expectation that the features and labels appear precisely as
the model_fn expects them. Features and labels can therefore be dicts of
tensors, or raw tensors.
Args
features
a dict of string to Tensor or Tensor.
labels
a dict of string to Tensor or Tensor.
default_batch_size
the number of query examples expected per batch. Leave
unset for variable batch size (recommended).