Question 1

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 2

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 3

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 4

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 5

How do you read TOML with tomllib in Python 3.11+?

Accepted Answer

**Target Audience:** Python developers who configure apps or tools, explained from zero
**Difficulty:** Easy
**Python version:** Behaviour checked on CPython 3.11, 3.12 and 3.13 (and in the page's Pyodide 3.11 runtime)

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:` so you also learn the exact words an interviewer expects. Every output block in the **Verified** section was copied from a real run of the examples on this page.

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Question 6

What is the difference between a list and a tuple?

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). Bytecode names are those of 3.11.

> **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** se

Question 7

What is the difference between __repr__ and __str__?

Accepted Answer

**Target Audience:** Beginners who have written a class or two, up to intermediate developers revising for interviews.
**Difficulty:** Easy
**Python version:** Behaviour checked on CPython 3.11 and 3.13 (identical output); every example also runs 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. When a word appears that an interviewer expects you to know, it is tagged with `📌 Interview term:` and defined right there. All

Question 8

How do you sort with a custom key, and how does sorted differ from sort?

Accepted Answer

**Target Audience:** Beginners to intermediate Python developers — you should know lists, tuples and simple functions.
**Difficulty:** Easy
**Python version:** Behaviour checked on CPython 3.11; the examples also run in the page on Pyodide 0.25.1 (CPython 3.11.3).

> **How to read this doc:** Each idea comes in plain language first. Words an interviewer expects you to know are tagged `📌 Interview term:` and defined on the spot; the Quick Glossary at the end lists them all. Every output and comp

Question 9

How do you convert between Python objects and JSON?

Accepted Answer

**Target Audience:** Beginners learning Python, and developers who want the edge cases an interviewer probes
**Difficulty:** Easy
**Python version:** Behaviour checked on CPython 3.11 (and in the page's Pyodide 3.11 runtime)

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:` so you also learn the exact words an interviewer expects. Every output block in the **Verified** section was copied from a real run of the examples on this page

Question 10

What do enumerate and zip do?

Accepted Answer

**Target Audience:** Beginners to intermediate Python developers preparing for interviews — you only need to know what a list and a `for` loop are.
**Difficulty:** Easy
**Python version:** Behaviour checked on CPython 3.11 (and 3.12 where noted); every example also runs 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. When a word appears that an interviewer expects you to know, it is tagged with `📌 Interview term:` and

PYTHONDECODED.

Easy

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

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

How does slicing with start:stop:step work?

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

How do you read TOML with tomllib in Python 3.11+?

What is the difference between a list and a tuple?

What is the difference between repr and str?

How do you sort with a custom key, and how does sorted differ from sort?

Medium

What is the difference between shallow and deep copy?

How do uv workspaces and named dependency groups work?

What are lambda functions and map/filter/reduce?

How does Python's name and object reference model work?

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

Hard

What is a weak reference in Python?