Question 1

break exits only the innermost loop

Accepted Answer

break exits only the innermost loop. The inner loop breaks when j == 1, but the outer loop continues normally. For each value of i (0, 1, 2), the inner loop runs j=0, then breaks at j=1, then print(i) runs. To break out of multiple loops you need a flag variable, a function return, or occasionally an exception.

Question 2

Falsy values in Python

Accepted Answer

All of those values are falsy in Python: 0, empty string, empty list, empty dict, None, False, and 0.0 all evaluate to False in a boolean context. None of them pass the 'if v' check, so count is 0. The full list of falsy values: None, False, 0 (int/float/complex), empty sequences ('', [], (), {}), and objects that define __bool__ returning False.

Question 3

any() and all() short-circuit

Accepted Answer

all() returns True if every element is truthy; it short-circuits on the first False. Every number in the list is even, so all(n % 2 == 0 ...) is True. any() returns True if at least one element is truthy; 6, 8, 10 are all > 5, so it's also True.

Question 4

Conditional expression (ternary)

Accepted Answer

The Python ternary expression is written as: value_if_true if condition else value_if_false. 7 % 2 is 1, which is != 0, so the condition is True and 'odd' is assigned to label. This is more concise than a two-line if-else for simple assignments.

Question 5

Short-circuit evaluation with and

Accepted Answer

Python's 'and' operator short-circuits: if the left operand is falsy, the right operand is never evaluated. Since False is the left operand and it's already False, side_effect() is never called and 'called' is never printed. The same applies to 'or': if the left side is truthy, the right side is skipped.

Question 6

enumerate() with a start value

Accepted Answer

enumerate() pairs each element with a counter. The optional start argument sets the initial counter value (default 0). With start=1, the first pair is (1, 'a'), then (2, 'b'), (3, 'c'). Use enumerate() instead of 'for i in range(len(items))' - it's cleaner and more Pythonic.

Question 7

continue skips the rest of the iteration

Accepted Answer

continue skips the remaining code in the current iteration and jumps to the next. When i is even (0, 2, 4) the print is skipped. When i is odd (1, 3) the print runs. This is cleaner than wrapping the loop body in 'if not (i % 2 == 0):'.

Question 8

match statement (Python 3.10+)

Accepted Answer

The match/case statement (structural pattern matching) was added in Python 3.10 via PEP 634. It goes well beyond a simple switch: you can match on structure, type, value, and destructure sequences and mappings in the same pattern. Before 3.10, the standard alternative was an if-elif chain or a dict dispatch.

Question 9

zip() stops at the shortest

Accepted Answer

zip() stops as soon as the shortest iterable is exhausted. Here b has only 2 elements, so the pair (3, ?) never forms. If you need to keep all elements from the longer iterable and fill the gap, use itertools.zip_longest with a fillvalue. The default zip behavior is the safe choice when you know the lengths match.

Question 10

Purpose of the pass statement

Accepted Answer

Python requires at least one statement inside any block (if, for, while, def, class, etc.). pass is a no-op statement that satisfies this requirement when you intentionally want an empty block - for example, a stub function or a class with no body yet. To exit a loop use break; to skip an iteration use continue; to suppress an exception use 'except: pass' (sparingly).

Question 11

Non-empty container is truthy

Accepted Answer

A container is truthy as long as it has at least one element - the truthiness of the elements inside doesn't matter. [0] is a non-empty list (truthy), {'k': 0} is a non-empty dict (truthy), and (False,) is a non-empty tuple (truthy). All five values pass the 'if v' check, so count is 5.

Question 12

Nested ternary expression

Accepted Answer

Python's ternary can be nested by placing another conditional expression in the else branch. n > 0 is False, so we move to the else. n < 0 is also False, so the inner else branch fires and 'zero' is returned. Nesting more than two levels deep gets hard to read quickly - an if-elif-else is usually clearer at that point.

Question 13

match with a wildcard

Accepted Answer

The _ pattern in a match block is the wildcard - it matches anything and is equivalent to a default branch. 'quit' doesn't match 'start' or 'stop', so the wildcard case runs and prints 'unknown'. There's no error if no case matches and no wildcard is present - the match block just does nothing.

Question 14

enumerate() default start

Accepted Answer

enumerate() without a start argument begins counting at 0. Wrapping it in list() materializes the lazy iterator into a list of (index, value) tuples. Each tuple pairs the zero-based position with the element at that position. This is exactly the structure you'd unpack in a for loop with 'for i, v in enumerate(colors):'.

Question 15

zip() with three iterables

Accepted Answer

zip() accepts any number of iterables and produces tuples where the nth tuple contains the nth element from each iterable. With three inputs of equal length, each output tuple has three elements. This is a common pattern for transposing columnar data or building a list of records from parallel arrays.

Question 16

pass inside an if block

Accepted Answer

pass is a genuine no-op - it occupies the if block syntactically but does absolutely nothing at runtime. Because x > 0 is True, the if branch runs (and does nothing), the else is skipped, and execution continues to print('done'). You'll see this pattern in stubs: write the structure first, fill in the logic later.