Question 1

What is the @property decorator?

Accepted Answer

**Target Audience:** Python beginners who know classes, up to candidates expected to explain descriptors
**Difficulty:** Medium
**Python version:** behaviour checked on CPython 3.11 (python3.11 and the in-page Pyodide 0.25.1 runtime); error messages also checked on 3.12 and 3.13

> **How to read this doc:** Every idea is first explained in plain words. When a term has a precise name an interviewer expects to hear, it is introduced as a 📌 **Interview term** callout. The Quick Glossary at the end

Question 2

What are decorators in Python?

Accepted Answer

**Target Audience:** Python beginners who have written functions, up to candidates preparing for mid-level interviews
**Difficulty:** Medium
**Python version:** behaviour checked on CPython 3.11 (python3.11 and the in-page Pyodide 0.25.1 runtime)

> **How to read this doc:** Every idea is first explained in plain words. When a term has a precise name an interviewer expects to hear, it is introduced as a 📌 **Interview term** callout. The Quick Glossary at the end lists all of them.

## 1. Why Th

Question 3

What is the difference between classmethod and staticmethod?

Accepted Answer

**Target Audience:** Beginners who know what `self` is, up to intermediate developers preparing for Python interviews.
**Difficulty:** Medium
**Python version:** Behaviour checked on CPython 3.11 and 3.13 (identical output except where a version is named); every in-page example also runs on Pyodide 0.25.1 (CPython 3.11.3).

> **How to read this doc:** Each idea is explained in plain language first. When a word appears that an interviewer expects you to know, it is tagged with `📌 Interview term:

Question 4

What does the functools module offer?

Accepted Answer

**Target Audience:** Python developers who write decorators, sort objects or cache expensive calls; candidates asked the open-ended "what is in functools?".
**Difficulty:** Medium
**Python version:** Behaviour checked on CPython 3.11.17 and in the page runner (Pyodide 0.25.1, CPython 3.11.3).

> **How to read this doc:** Each idea is explained in plain words first, then tagged with `📌 Interview term:` — that is the exact vocabulary an interviewer expects to hear. Every output shown was printed

Question 5

What does __slots__ do?

Accepted Answer

**Target Audience:** Python developers who know classes and instance attributes and want to understand what `__slots__` changes under the hood.
**Difficulty:** Medium
**Python version:** Behaviour checked on CPython 3.11.17, 3.12 and 3.13, and in the page runner (Pyodide 0.25.1, CPython 3.11.3). Memory figures are from our CPython runs and vary by version.

> **How to read this doc:** Every idea is explained in plain language first, then tagged with `📌 Interview term:` so you also learn the exa

Question 6

How do TypeAdapter, strict mode, and computed fields work in Pydantic v2?

Accepted Answer

**Target Audience:** Developers who know basic Pydantic `BaseModel` usage and want the v2 features interviewers ask about next.
**Difficulty:** Hard
**Python version:** Pydantic examples run on CPython 3.13 with **pydantic 2.13.5** (pydantic-core 2.46.5). Pydantic is a third-party package, so those examples cannot run in the page; the first example is standard library only and runs in the page (Pyodide 0.25.1, CPython 3.11.3).

> **How to read this doc:** Every idea is explained in plain languag

Question 7

What is the difference between __getattr__ and __getattribute__?

Accepted Answer

**Target Audience:** Intermediate Python developers who know classes and methods and have seen `__getattr__` in library code.
**Difficulty:** Hard
**Python version:** Behaviour checked on CPython 3.11 (outputs identical on 3.12 and 3.13); both examples also run in the page on Pyodide 0.25.1 (CPython 3.11.3).

> **How to read this doc:** Ideas come in plain language first. Terms an interviewer expects you to use are tagged `📌 Interview term:` and defined where they appear; the Quick Glossary rep

Question 8

How does attribute lookup work on a Python object?

Accepted Answer

**Target Audience:** Intermediate Python developers who know what a class, an instance and a method are, and want the exact rules an interviewer probes.
**Difficulty:** Hard
**Python version:** Behaviour and bytecode checked on CPython 3.11 (and 3.12/3.13 where noted); both examples also run in the page on Pyodide 0.25.1 (CPython 3.11.3).

> **How to read this doc:** Every idea comes in plain language first. Words an interviewer expects you to use are tagged `📌 Interview term:` and defined on t

Question 9

What is the descriptor protocol?

Accepted Answer

**Target Audience:** Intermediate Python developers who use `@property` and methods every day and want to know the machinery under them.
**Difficulty:** Hard
**Python version:** Behaviour checked on CPython 3.11 (outputs identical on 3.12 and 3.13); both examples also run in the page on Pyodide 0.25.1 (CPython 3.11.3).

> **How to read this doc:** Plain-language explanation comes first. The vocabulary an interviewer expects is tagged `📌 Interview term:` and defined on the spot; all terms are co

PYTHONDECODED.

Medium