That page is actually quite old (I am trying to remove it
https://github.com/sympy/sympy/pull/2807).
My advice is that the core is the worst place to start if you are
trying to understand the code in SymPy. It is by far the hardest to
understand. I would start with one of the high-level modules that
interested you (solvers, simplify, stats, sets, etc.), and only once
you understand how to use SymPy in a high-level way, then start to try
to understand how the core works.
The best place to start is with the tutorial, as that will show you
how to use SymPy as a user. Since SymPy uses itself, this is important
even if you wish to develop on SymPy.
Aaron Meurer
>
https://groups.google.com/d/msgid/sympy/CAP7f1AhxAfYxjw8p8eoNH66Ws34O151QDwQE7JMAy-6HUMFbvw%40mail.gmail.com.