Today I learned how to debug the new Python REPL with _pyrepl.trace and the environment variable PYREPL_TRACE.
_pyrepl.trace
PYREPL_TRACE
Today I learned how to fix an issue with Ctrl+left and Ctrl+right not working in the new Python REPL on MacOS.
You didn't ask, but let me tell you I learned a lot of maths over at KhanAcademy.