This is an extension of an animation library used by math YouTuber 3blue1brown [0]. He has an excellent channel that I would recommend anything from. One of my favorite videos of his is where he shows the thought process behind solving a level 6 Putnam competition problem and makes it seem almost doable [1].
I've never been able to get into these animated videos of 3b1b, but the more recent videos with a more conversational tone (Lockdown math, the MIT Computational thinking course, the podcast) have made me a big fan of Grant.