minor update

    pip install git+https://github.com/korepwx/tfsnippet.git

    pip install .

This will first install `ZhuSuan`_ and `TFSnippet`_, the two major dependencies

This will first install `ZhuSuan <https://github.com/thu-ml/zhusuan>`_ and

`TFSnippet <https://github.com/korepwx/tfsnippet>`_, the two major dependencies

of Donut, then install the Donut package itself.

_`ZhuSuan`: https://github.com/thu-ml/zhusuan

_`TFSnippet`: https://github.com/korepwx/tfsnippet

API Usage

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