Here's what I worked on. My demo wasn't great due to some oversights (failing to warm up the cache, a bug in the code, not having had a breakthrough on compilation), but I had a breakthrough the night after the hackathon demos, and here's the result.
Hi, this open task is tagged only with Wikimania-Hackathon-2019 which is in the past.
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Thank you for helping clean up a bit! :)