[Clarification] Question id 443 dev set

Hi Bird team,

In question 443 in the dev set (“Give the code of sets that have expansion type ‘expansion’?”) for the “card_games” database, the gold SQL is:

SELECT T2.setCode
FROM sets AS T1
INNER JOIN set_translations AS T2 ON T2.setCode = T1.code
WHERE T1.type = 'expansion'
GROUP BY T2.setCode;

Could you clarify why joining to set_translations is necessary here?

The sets table already contains a `code` column whose description matches “setCode”, and the question does not ask for translations. Is the join required only to satisfy an annotation/evidence mapping that expects the output column name to be `setCode`, or is there a data rule that a set code is only considered valid if it appears in set_translations?

Thanks!