Support Colab

[jonmmease]

I tried vegafusion-jupyter==0.0.1a1 in Google Colab. Colab is successfully able to load the extension from a CDN, and the widget is displayed

But the comm message is not successfully sent from the client to the server. Here is the browser console message

There's not a lot to go on to debug this unforntunately

[jonmmease]

This error happens when using the send method to send a custom message from client to server. I think Colab supports this since they support Jupyter Comms, but we might have better luck being compatible with non-native jupyter contexts if we use traitlet properties to communicate between client and server.

[dwootton]

One comment on here for anyone using it in colab, you'll need to add vegafusion-python-embed to the packages to install.
Following the quick start in the readme, your pip install will become:
pip install vegafusion-jupyter vega-datasets vegafusion-python-embed

Example Colab here

Thanks @jonmmease for solving this bug before I even ran into it 👍