Why Python Questions Reveal More Than Any Resume Line

class Account:
    def __init__(self, owner, balance=0):
        self.owner = owner
        self.balance = balance       # goes through the setter below

    @property
    def balance(self):
        return self._balance

    @balance.setter
    def balance(self, value):
        if value < 0:
            raise ValueError("balance cannot be negative")
        self._balance = value

acc = Account("Asha", 500)
acc.balance = 300        # validated
print(acc.balance)       # 300

try:
    acc.balance = -50
except ValueError as e:
    print(e)             # balance cannot be negative

Q: When would you use @property?

Weak: "It makes a method into a property."
-> Knows the word.

Decent: "To add getters and setters in Python."
-> Knows the purpose, sounds like Java thinking.

Strong: "When I want attribute syntax but need logic
behind it, like validating a balance or computing a
full name. It also lets me start with a plain
attribute and add validation later without changing
any code that uses the class."
-> Has designed and evolved a class.

employees = [
    {"name": "Ravi",  "dept": "QA",  "salary": 42000},
    {"name": "Asha",  "dept": "Dev", "salary": 55000},
    {"name": "Karan", "dept": "Dev", "salary": 61000},
    {"name": "Meena", "dept": "QA",  "salary": 48000},
]

ranked = sorted(employees, key=lambda e: (e["dept"], -e["salary"]))
for e in ranked:
    print(e["dept"], e["name"], e["salary"])
# Dev Karan 61000
# Dev Asha 55000
# QA Meena 48000
# QA Ravi 42000

# For non-numeric descending fields, use two stable sorts:
# sort by the secondary key first, then by the primary key.
by_name_desc = sorted(employees, key=lambda e: e["name"], reverse=True)
final = sorted(by_name_desc, key=lambda e: e["dept"])

import functools
import time

def timed(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):          # accept anything
        start = time.perf_counter()
        result = func(*args, **kwargs)     # pass it all through
        print(f"{func.__name__} took {time.perf_counter() - start:.4f}s")
        return result
    return wrapper

@timed
def build_report(rows, *, title="Report"):
    return f"{title}: {len(rows)} rows"

print(build_report([1, 2, 3], title="Sales"))

# Spoken: "The wrapper does not know build_report's
# signature, so *args and **kwargs collect whatever is
# passed and forward it unchanged."

Q: What is the difference between sort() and sorted()?

A: sort() is a list method and sorted() is a
built-in function.

(True, but it does not say anything about
behaviour, and nothing about experience.)

Q: What is the difference between sort() and sorted()?

A: sort() sorts a list in place and returns None.
sorted() takes any iterable and returns a new list,
leaving the original alone.

I learned the None part the hard way: I wrote

    return scores.sort(reverse=True)

in a Flask route, and the API returned null. The fix
was to sort first and then return the list, or use
return sorted(scores, reverse=True).

I use sorted() when other code still needs the
original order.

KEYWORD MAP

Keyword          Likely question
OOP          ->  ______________________________
Flask/Django ->  ______________________________
pandas       ->  ______________________________
SQL          ->  ______________________________
Git          ->  ______________________________
APIs         ->  ______________________________
Testing      ->  ______________________________

Answer each aloud in under 60 seconds.
If you cannot, practise it or remove the keyword.

EVIDENCE CARD (one per keyword)

Keyword: ______________
Project where I used it: ______________
What I built with it: ______________
A bug or surprise it caused: ______________
How I fixed it: ______________
A choice I made (X over Y) and why:
  ________________________________

One-line evidence sentence:
  ________________________________

QUICK SELF-TEST (no notes)

[ ] Write a class with a validated @property
[ ] Sort a list of dicts by two keys, one descending
[ ] Write a decorator that uses *args and **kwargs
[ ] Create a venv and a pinned requirements file
[ ] Explain sort() returning None with an example
[ ] Use enumerate and zip in one loop
[ ] Read a JSON file and handle a missing key

Each one you cannot do in 10 minutes is a keyword
that may not survive its first question.