Question 1

What are list/dict/set comprehensions?

Accepted Answer

**Target Audience:** Beginners to intermediate Python developers — you should be comfortable with `for` loops and lists.
**Difficulty:** Easy
**Python version:** Behaviour checked on CPython 3.11, with the scope and bytecode differences also run on 3.12 and 3.13; the examples run in the page on Pyodide 0.25.1 (CPython 3.11.3).

> **How to read this doc:** Every idea is explained in plain language first, then the precise word an interviewer expects is tagged `📌 Interview term:` and defined. The

Question 2

What is the walrus operator?

Accepted Answer

**Target Audience:** Beginners who have seen `:=` and want to know when it helps; candidates who want the scope and syntax rules.
**Difficulty:** Easy
**Python version:** Available since Python 3.8. Behaviour checked on CPython 3.11.17 (and 3.13.16, same output) and in the page runner (Pyodide 0.25.1, CPython 3.11.3).

> **How to read this doc:** Every idea is explained in plain words, then tagged `📌 Interview term:` with the name an interviewer expects. All output is from real runs, collected

Question 3

What is the LEGB rule for scope resolution?

Accepted Answer

**Target Audience:** Python beginners and intermediate developers preparing for interviews — you only need to know what a function is.
**Difficulty:** Medium
**Python version:** Behaviour checked on CPython 3.11, 3.12 and 3.13; the examples run in the page on Pyodide 0.25.1 (CPython 3.11.3).

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:` so you also learn the exact word an interviewer expects. Every output shown was produced by

Question 4

What is Python 3.12's new type parameter syntax (type, generic classes)?

Accepted Answer

**Target Audience:** Python developers who know `TypeVar` and `Generic` and are moving a codebase to Python 3.12 or later.
**Difficulty:** Medium
**Python version:** The syntax needs **Python 3.12+** (defaults need 3.13+). Examples 2 and 3 were run on CPython 3.12.3 and 3.13.16 and are shown as code here, because the page runner is Pyodide 0.25.1 (CPython 3.11.3), where the syntax is a `SyntaxError`. Example 1 runs in the page. Type-checker output is from mypy 2.3.1.

> **How to read this doc:**

Question 5

What is monkey patching in Python?

Accepted Answer

**Target Audience:** Developers who have seen `mock.patch` in tests or a "quick fix" that reassigns a library function, up to candidates who must explain scope, the import trap and the risks.
**Difficulty:** Medium
**Python version:** Behaviour checked on CPython 3.11 (python3.11 and the in-page Pyodide 0.25.1 runtime, which is CPython 3.11.3); spot checks on 3.12 and 3.13 are noted.

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:

PYTHONDECODED.

Easy

What are list/dict/set comprehensions?

What is the walrus operator?

Medium

What is the LEGB rule for scope resolution?

What is Python 3.12's new type parameter syntax (type, generic classes)?

What is monkey patching in Python?