I thought I spotted a bug on the very first day, part 2. def day1_2(nums): "Find 3 distinct numbers that sum to 2020, and return their product." retu

I thought I spotted a bug on the very first day, part 2. def day1_2(nums): "Find 3 distinct numbers that sum to 2020, and return their product." return first(x * y * z for x, y in combinations(nums, 2) for z in nums & {2020 - x - y} if x != z != y) The last line (if x != z != y) returns true when x and y are equal and z is different. But x and y are already constrained to be different since nums is a set and itertools combinations picks distinct elements from the iterable. If the test had been x != y != z it would have been a bug.