It’s code. L-System. https://en.wikipedia.org/wiki/L-system
It’s string manipulation usually for the purposes of drawing – controlling a “turtle”.
It can _also_ be implemented in various languages, but it’s its own native language.
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There’s an implementation of it in Inkscape under Rendering. You can take that code directly from the picture, change the |-> into an = but otherwise the same. Plug everything in, and it outputs the same tree.
So it’s not math per se but it is computing.
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