A couple of Hacker Schoolers were discussing an interesting corner of python today. We discovered a nice bit of trivia: there exist three lines of python code that display the following behavior:

1
2
3
4
5
6
7
8
9
10
11
12

>>> LINE_A
>>> LINE_B
>>> LINE_C
False
>>> LINE_A; LINE_B; LINE_C
True
>>> def my_function():
...     LINE_A
...     LINE_B
...     LINE_C
>>> my_function()
True

What are the lines?

Some ground rules:

• Introspection of any kind is cheating (e.g. noting the line number).
• No dunder (__foo__) methods allowed.
• Each line is a valid python expression.
• You can’t rely on order: while the lines will always execute A –> B –> C, a complete solution behaves identically if e.g. the semicolon version happens before the separate-line version.
• No cheating with the function: e.g. you can’t add a return unless you add it everywhere.
• Edit: And nothing stateful.

For bonus points, code golf! My solution to this is 14 19 characters long, not counting whitespace.