[DO NOT REVIEW] Introduce multiple streams execution in TensorFlow.
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Multiple Stream TensorFlow is developed based on the official [TensorFlow 2.2](https://github.com/tensorflow/tensorflow/tree/r2.2). It leverages the features of modern GPUs to accelerate deep learning training and inference. This Multi-Stream implementation has successfully helped several customers migrate their TF models to the GPU and go online.

For more details please visit [README_MultiStream.md](https://github.com/buptzyb/tensorflow/blob/r2.2_multistream/README_MultiStream.md).