Python foundations: check what you know

Already know some Python? Answer these 15 questions, about 8 minutes. Each topic you get fully right is marked Known on the Python roadmap, so you can skip it. Each one you miss is listed for you to study.

Don’t guess. Pick “I don’t know yet” when you’re not sure: a lucky guess would mark a topic Known that you still need to learn.

The 16 topics it checks

1. Install Python and run your first file
2. Variables, print() and input()
3. Decisions and loops: if, for and while
4. Numbers, strings, slicing and f-strings
5. Your first functions: def and return
6. list, tuple, dict and set, and what each operation costs
7. How Python runs your code
8. Names, objects and references
9. Mutable and immutable objects
10. Functions, *args, **kwargs and the mutable-default trap
11. Scope and the LEGB rule
12. Comprehensions
13. Exceptions
14. Files and pathlib
15. Modules, packages and virtual environments
16. Git for everyday work: commit, branch, merge, rebase, pull requests

1. Question 1 of 15 · Predict the outputYou run python app.py. Line 2 has a typo in a name. What happens?

   print("start")
   pritn("end")
   

   Nothing prints. Python finds the typo before it runs anything."start" prints, then Python stops with a NameError on line 2.Both lines print.Python skips line 2 and continues.I don’t know yet
2. Question 2 of 15 · Predict the outputThe user types 30. What happens?

   age = input("Age? ")
   print(age + 1)
   

   It prints 31.It prints 301.It stops with a TypeError.It prints age1.I don’t know yet
3. Question 3 of 15 · Predict the outputWhat does this print?

   word = "python"
   print(f"{word[1:4]}-{len(word)}")
   

   yth-6pyt-6ytho-6yth-5I don’t know yet
4. Question 4 of 15 · Predict the outputWhat does this print?

   total = 0
   for n in range(1, 5):
       if n % 2 == 0:
           continue
       total += n
   print(total)
   

   10964I don’t know yet
5. Question 5 of 15 · Predict the outputWhat does this print?

   def area(w, h):
       w * h
   
   print(area(3, 4))
   

   None120Nothing; it stops with an error.I don’t know yet
6. Question 6 of 15 · Multiple choiceYou will check thousands of times whether a user id is in a group of a million ids. Which container makes each check fastest?

   A listA tupleA string with the ids joined by commasA setI don’t know yet
7. Question 7 of 15 · Multiple choiceEach container holds a million items. Which of these takes about a million steps, not one?

   prices[key] on a dictitems.append(x) on a listitems.insert(0, x) on a listseen.add(x) on a setI don’t know yet
8. Question 8 of 15 · Predict the outputWhat does this print?

   a = [1, 2]
   b = a
   b.append(3)
   print(a)
   

   [1, 2][1, 2, 3][1, 2, [3]]Nothing; it stops with an error.I don’t know yet
9. Question 9 of 15 · Predict the outputWhat does this print?

   def add(item, bag=[]):
       bag.append(item)
       return bag
   
   add("a")
   print(add("b"))
   

   ['b']['a'][]['a', 'b']I don’t know yet
10. Question 10 of 15 · Predict the outputWhat does this print?

    def show(first, *args, **kwargs):
        print(first, args, kwargs)
    
    show(1, 2, 3, color="red")
    

    1 [2, 3] {'color': 'red'}1 (2, 3) {'color': 'red'}1 2 3 color=red(1, 2, 3) {'color': 'red'}I don’t know yet
11. Question 11 of 15 · Predict the outputWhat happens when bump() runs?

    count = 0
    
    def bump():
        count += 1
    
    bump()
    

    count becomes 1.count stays 0 and nothing goes wrong.It stops with an UnboundLocalError.It makes a new global count of 1.I don’t know yet
12. Question 12 of 15 · Predict the outputWhat does this print?

    print([x * x for x in range(6) if x % 2])
    

    [1, 9, 25][0, 4, 16][1, 4, 9, 16, 25][0, 1, 4, 9, 16, 25]I don’t know yet
13. Question 13 of 15 · Predict the outputnotes.txt does not exist. What happens?

    try:
        with open("notes.txt") as f:
            text = f.read()
    except FileNotFoundError:
        text = ""
    finally:
        print("done")
    print(len(text))
    

    It stops with a FileNotFoundError.It prints 0 only.It prints done, then 0.It prints done, then stops because text was never set.I don’t know yet
14. Question 14 of 15 · Multiple choiceYou made a virtual environment in .venv, installed requests, and now make your first git commit. What should the commit hold?

    requirements.txt (or pyproject.toml) with requests listed, and .venv in .gitignore.The .venv folder, so others get the same packages.Nothing about packages; git records what you installed.Both the .venv folder and requirements.txt.I don’t know yet
15. Question 15 of 15 · Multiple choiceYour branch has 3 commits. Meanwhile a teammate added 2 commits to main. What is the difference between git merge main and git rebase main on your branch?

    merge deletes your 3 commits; rebase keeps them.They do the same thing; rebase is only faster.rebase sends your branch to GitHub; merge does not.merge adds a new commit that joins the two histories; rebase replays your 3 commits on top of main, as new commits.I don’t know yet

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Answered 0 of 15.