const auto signature_def_map = metagraph_def.signature_def();
  const auto signature_def = signature_def_map.at("regress_x_to_y");

  const std::string input_name =
      signature_def.inputs().at(tensorflow::kRegressInputs).name();
  const std::string output_name =
      signature_def.outputs().at(tensorflow::kRegressOutputs).name();