Exercise deviations from problem specs

[tasxatzial]

In this issue, i'll be collecting any deviations from the problem specifications for each exercise. This will serve as a reference, making it easier to see the differences without sifting through piles of old PRs.

Please create separate issues for discussions, and edit my comment below to add new exercises alphabetically.

[tasxatzial]

allergies

Issue 1

Problem specs mention "list when" in some test descriptions. This implies to return a list. However the tests are using vectors as output.
Solution: Added instructions.append (#693)

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[tasxatzial]

Reserved in case we run out of space in the previous comment