AEC3 neural residual echo estimator

[thunde...@gmail.com]

I'm directly calling an AEC3 instance and I see references in the code to a neural residual echo estimator. e.g. 

absl_nullable std::unique_ptr<NeuralResidualEchoEstimator>
CreateNeuralResidualEchoEstimator(absl::string_view tflite_model_path,
                                  const tflite::OpResolver* absl_nonnull
                                      op_resolver);

What tflite file does it expect? Is there something in the build I'm missing?

Thanks