Py Internals An open-source, interactive Python course that shows what your code does in memory. https://inboxpraveen.github.io/Py-Internals/ 2026-10-17T00:00:00Z Praveen Kumarhttps://github.com/inboxpraveen Session 09: Modules & Imports https://inboxpraveen.github.io/Py-Internals/sessions/09-modules/ 2026-10-17T00:00:00Z 2026-10-17T00:00:00Z What import really does: find a file, run it once, cache it in sys.modules and bind a name. Why from-imports go stale, what __name__ is, and how circular imports break. Session 08: Exceptions, Tracebacks & Context Managers https://inboxpraveen.github.io/Py-Internals/sessions/08-exceptions/ 2026-09-17T00:00:00Z 2026-10-17T00:00:00Z What raise does to the call stack, how to read a traceback, why finally runs past a return, what with calls for you and how exceptions chain with from. Session 07: The GIL & Concurrency https://inboxpraveen.github.io/Py-Internals/sessions/07-gil/ 2026-09-12T00:00:00Z 2026-10-17T00:00:00Z Why CPython has a global interpreter lock, why it doesn't make your code thread-safe, and when threads, multiprocessing or asyncio actually help. Session 06: Decorators https://inboxpraveen.github.io/Py-Internals/sessions/06-decorators/ 2026-09-03T00:00:00Z 2026-10-17T00:00:00Z A decorator is one line of assignment. See the wrapper, the closure cell that keeps your function alive, functools.wraps, decorator factories and stacking. Session 04: Classes & Objects https://inboxpraveen.github.io/Py-Internals/sessions/04-classes/ 2026-08-15T00:00:00Z 2026-10-17T00:00:00Z What self really is, where attributes live, how bound methods work, why class attributes are shared and how inheritance is just a longer lookup. Session 05: Iterators & Generators https://inboxpraveen.github.io/Py-Internals/sessions/05-iterators/ 2026-08-15T00:00:00Z 2026-10-17T00:00:00Z How a for loop uses iter and next, what StopIteration does, how yield pauses a frame and what lazy evaluation costs in memory compared with a list. Session 03: Lists, Dicts & References https://inboxpraveen.github.io/Py-Internals/sessions/03-lists-dicts/ 2026-05-07T00:00:00Z 2026-10-17T00:00:00Z Why b = a shares a list, what a shallow copy really copies, how deepcopy differs, and why passing a dict to a function can change the caller's data. Session 02: Functions, Scope & the Call Stack https://inboxpraveen.github.io/Py-Internals/sessions/02-functions/ 2026-05-05T00:00:00Z 2026-10-17T00:00:00Z Watch a call frame appear and disappear. Local scope, LEGB lookup, arguments passed by reference, closures with real cells and the mutable default trap. Session 01: Variables & Mutability https://inboxpraveen.github.io/Py-Internals/sessions/01-variables/ 2026-03-23T00:00:00Z 2026-10-17T00:00:00Z See what x = 42 really does in memory. Names, objects, id(), aliasing, mutation versus rebinding and reference counting, animated one step at a time.