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The Python wat quiz

Test your knowledge of Python edge cases!

Instructions

In each of the 12 snippets below, one or more values is missing (marked with ???). In each case, answer Yes or No: is it possible to replace the ??? with an expression using basic, built-in Python types (see Details below) that will make the snippet into exactly what you would see if you entered the text into the interpreter?

Examples

Example question 1

>>> x, y = ???
>>> x + y == y + x
False

Example answer 1

Yes. This snippet is possible.

>>> x, y = [0], [1]
>>> x + y == y + x
False

Example question 2

>>> x = ???
>>> x < x
True

Example answer 2

No. This snippet is impossible.

Details and scope

Now, technically, type("", (), {"__lt__": lambda a, b: True})() would make Example question 2 work. But don't worry. This quiz is not about trick questions, and I'm not looking for "trick" answers like that. The missing values in this quiz are limited to the built-in types bool, int, list, tuple, dict, set, frozenset, str, and NoneType, and values of these types.

In particular, the following are out of scope, and are not valid as missing values:

  • floats, including nan and inf
  • unicode (Strings, if they appear, only have ascii characters.)
  • the type keyword
  • user-defined classes
  • lambdas
  • anything using globals or locals
  • anything using import
  • anything that changes value just by inspecting it or iterating over it (iterators and generators)
  • expressions with side effects (e.g. eval), including anything that redefines built-ins (obviously)
  • bytes arrays, buffers, ranges, memoryviews, and dictionary views

Again, these are not trick questions. For snippets whose answers are Yes, this is possible, the missing values will clearly be in scope.

Assume the latest Python version (currently 3.5) if it matters. It shouldn't, though.

The questions

Make sure to write down your answers (Yes or No) before looking at the answers, so you're not tempted to cheat.

For a real challenge, try taking the quiz without using a Python interpreter to check your answers.

Good luck!

Question 1: min of two elements

>>> x, y = ???
>>> min(x, y) == min(y, x)
False

Question 2: size of sets and lists

>>> x = ???
>>> len(set(list(x))) == len(list(set(x)))
False

Question 3: type vs map

>>> x, s = ???
>>> s.add(x)
>>> type(x) in map(type, s)
False

Question 4: zip vs comparison

>>> x, y = ???
>>> x < y and all(a >= b for a, b in zip(x, y))
True

Question 5: zero sum

>>> x, y = ???
>>> sum(0 * x, y) == y
False

Question 6: argument expansion

>>> x = ???
>>> min(x) == min(*x)
False

Question 7: Associative multiplication

>>> x, y, z = ???
>>> x * (y * z) == (x * y) * z
False

Question 8: max vs in

>>> x, y = ???
>>> y > max(x) and y in x
True

Question 9: any vs addition

>>> x, y = ???
>>> any(x) and not any(x + y)
True

Question 10: count vs len

>>> x, y = ???
>>> x.count(y) <= len(x)
False

Question 11: all vs filter

>>> x = ???
>>> all(filter(None, x))
False

Question 12: max vs slice

>>> x, a, b, c = ???
>>> max(x) < max(x[a:b:c])
True

Answers

All done? Make sure you have your answers written down and check out the answers here.