I think it was a big mistake for D3 to move all of their examples to Observable.
People who want to learn D3 and are unfamiliar with Observable now have to untangle what's Observable and what's D3 from the examples. It was much easier to get started when you copy a bl.ock and make a few changes in your own app.
And Observable has some serious non-standard voodoo you have to untangle.
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