[HuShifang]

As it happens, there's a PyMC implementation of the 1st and 2nd editions of Statistical Rethinking here:

https://github.com/pymc-devs/pymc-resources

(I think the author of the book discussed above, Osvaldo Martin, is the primary or sole contributor for the Rethinking implementations, in fact -- he had a full implementation in his own repo (https://github.com/aloctavodia/Statistical-Rethinking-with-P...) before deprecating it in favor of the above-linked one.)