Question 1

What is the difference between a module and a package?

Accepted Answer

**Target Audience:** Beginners learning Python, and anyone preparing for a Python interview
**Difficulty:** Easy
**Python version:** Every example was run on CPython 3.11 (and in this page on Pyodide 0.25.1, which is 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 block in the **Verified** section was copied from a real run of the examples on th

Question 2

What is duck typing in Python?

Accepted Answer

**Target Audience:** Beginners who know functions and classes, and anyone who wants a crisp interview definition with real examples.
**Difficulty:** Easy
**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).

> **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 in the **Verified** section w

Question 3

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 4

What are mixins in Python?

Accepted Answer

**Target Audience:** Developers who know single inheritance and want to use (and explain) multiple inheritance the way Python libraries do.
**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).

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

Question 5

What is structural pattern matching (match/case)?

Accepted Answer

**Target Audience:** Python developers who know `if`/`elif`, lists, dicts and classes and have never used `match`, plus anyone who wants the exact rules an interviewer probes.
**Difficulty:** Medium
**Python version:** `match` needs Python 3.10+. Behaviour and bytecode checked on CPython 3.11 (gotchas re-run on 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. The words an interviewer expects you to use

Question 6

What is composition versus inheritance?

Accepted Answer

**Target Audience:** Developers who can write classes and subclasses and want to know how to choose between the two main ways of reusing code.
**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).

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

Question 7

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 8

What are common Python security pitfalls?

Accepted Answer

**Target Audience:** Developers who write Python services or scripts and want a concrete checklist; no security background assumed.
**Difficulty:** Medium
**Python version:** Examples 1 and 2 were run on CPython 3.11 (python3.11 and the in-page Pyodide 0.25.1 runtime, CPython 3.11.3). Example 3 needs `sqlite3` and the `tarfile` filters, which the page runtime does not have, so it was run on python3.12 (and gave identical output on python3.13).

> **How to read this doc:** Each idea is explained

Question 9

What is the difference between __new__ and __init__?

Accepted Answer

**Target Audience:** Python developers who write classes with `__init__` and have seen `__new__` in library code or an interview question.
**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).

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

Question 10

What are dataclasses?

Accepted Answer

**Target Audience:** Python developers who write classes by hand and want to know what `@dataclass` generates, which options matter, and where its limits are.
**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). `slots`, `kw_only` and `KW_ONLY` need 3.10+.

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

PYTHONDECODED.

Easy

What is the difference between a module and a package?

What is duck typing in Python?

What is the walrus operator?

Medium

What are mixins in Python?

What is structural pattern matching (match/case)?

What is composition versus inheritance?

What is the LEGB rule for scope resolution?

What are common Python security pitfalls?

What is the difference between new and init?

What are dataclasses?

How do you create and chain custom exceptions?

Hard

What is the difference between getattr and getattribute?

How does attribute lookup work on a Python object?

What is the descriptor protocol?

What is __init_subclass__ in Python?

PYTHONDECODED.

Easy

What is the difference between a module and a package?

What is duck typing in Python?

What is the walrus operator?

Medium

What are mixins in Python?

What is structural pattern matching (match/case)?

What is composition versus inheritance?

What is the LEGB rule for scope resolution?

What are common Python security pitfalls?

What is the difference between __new__ and __init__?

What are dataclasses?

How do you create and chain custom exceptions?

Hard

What is the difference between __getattr__ and __getattribute__?

How does attribute lookup work on a Python object?

What is the descriptor protocol?

What is __init_subclass__ in Python?

What is the difference between new and init?

What is the difference between getattr and getattribute?