Question 1

What are common useful string methods?

Accepted Answer

**Target Audience:** Beginners preparing for Python interviews — no prior knowledge assumed beyond what a variable is.
**Difficulty:** Easy
**Python version:** Checked on CPython 3.11 and on the page runner (Pyodide 0.25.1 = CPython 3.11.3). `removeprefix`/`removesuffix` need 3.9 or newer.

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

Question 2

What is the difference between '==' and 'is'?

Accepted Answer

**Target Audience:** Beginners preparing for Python interviews — no prior Python knowledge assumed.
**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); the warning text was also checked on 3.12.

> **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 in the **Veri

Question 3

What are mutable and immutable types in Python?

Accepted Answer

**Target Audience:** Beginners preparing for Python interviews — no prior Python knowledge assumed.
**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 shown in the **Verified** section was copied from a real run o

Question 4

How do you work with dictionaries (get, setdefault, items, merging)?

Accepted Answer

**Target Audience:** Beginners preparing for Python interviews — no prior knowledge assumed beyond variables and lists.
**Difficulty:** Easy
**Python version:** Checked on CPython 3.11 and the page runner (Pyodide 0.25.1 = CPython 3.11.3). The `|` and `|=` operators need Python 3.9 or newer.

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

Question 5

Why use virtual environments?

Accepted Answer

**Target Audience:** Beginners setting up their first Python projects, and anyone preparing for a Python interview
**Difficulty:** Easy
**Python version:** Example 1 was run on CPython 3.11 and in this page (Pyodide 0.25.1, CPython 3.11.3); Example 2 creates a real environment, so it was run on CPython 3.12 outside the browser. The shell output below is from python3.11 on Linux.

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

Question 6

How does slicing with start:stop:step work?

Accepted Answer

**Target Audience:** Beginners preparing for Python interviews — you only need to know what a list and a string are.
**Difficulty:** Easy
**Python version:** Checked on CPython 3.11 and the page runner (Pyodide 0.25.1 = CPython 3.11.3); the bytecode comparison was also run on CPython 3.12.

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

Question 7

What is the difference between append, extend and insert on a list?

Accepted Answer

**Target Audience:** Beginners preparing for Python interviews — you need to know what a list is; nothing more.
**Difficulty:** Easy
**Python version:** Checked on CPython 3.11 (64-bit Linux) and the page runner (Pyodide 0.25.1 = CPython 3.11.3, a 32-bit WebAssembly build).

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

Question 8

How does iterable unpacking work?

Accepted Answer

**Target Audience:** Beginners to intermediate Python developers — you should know what a list and a tuple are.
**Difficulty:** Easy
**Python version:** Behaviour and `dis` output checked on CPython 3.11 (3.12 where noted); the 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. Words an interviewer expects you to use are tagged `📌 Interview term:` and defined on the spot, then listed again in the Quick Glossary. All

Question 9

What is the enum module and when should you use it?

Accepted Answer

**Target Audience:** Python beginners and intermediate developers who use strings or numbers as status codes and want to know what `enum` adds
**Difficulty:** Easy
**Python version:** Checked on CPython 3.11 (and in this page on Pyodide 0.25.1, which is CPython 3.11.3); differences in 3.12 are called out where we ran them

> **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. Ever

Question 10

How do break, continue, pass and loop else work?

Accepted Answer

**Target Audience:** Beginners learning Python control flow; also a quick refresher before an interview.
**Difficulty:** Easy
**Python version:** Behaviour checked on CPython 3.11.17 and in the page runner (Pyodide 0.25.1, CPython 3.11.3); the `finally` note was also checked against the 3.14 release notes.

> **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 show

PYTHONDECODED.

Easy

What are common useful string methods?

What is the difference between '==' and 'is'?

What are mutable and immutable types in Python?

How do you work with dictionaries (get, setdefault, items, merging)?

Why use virtual environments?

How does slicing with start:stop:step work?

What is the difference between append, extend and insert on a list?

How does iterable unpacking work?

Medium

What is the difference between shallow and deep copy?

What is a race condition and how do locks prevent it?

What are mixins in Python?

How do uv workspaces and named dependency groups work?

What is the difference between an iterable and an iterator?

What are dunder (magic) methods?

What is structural pattern matching (match/case)?

How does Pydantic v2 validation work (BaseModel, field_validator, mode)?

Hard

How does Python manage memory and garbage collection?

What is an async iterator and async for?

How does the Python import system work?

What is a metaclass?

How does typing.Never enable exhaustive match checking?

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

What is a weak reference in Python?

How does CPython execute your code?