Add a demo file
Add a demo file

jupyter/jupyter-js-plugins,blink1073/jupyter-js-plugins,blink1073/jupyter-js-plugins,blink1073/jupyter-js-plugins,jupyter/jupyter-js-plugins,blink1073/jupyter-js-plugins,blink1073/jupyter-js-plugins,jupyter/jupyter-js-plugins,jupyter/jupyter-js-plugins,jupyter/jupyter-js-plugins