سؤال 41

If `data = dict(a=1)`, what happens when `data["b"]` is evaluated?

It raises `KeyError`.پاسخ درست
It returns `None`.
It inserts `b` with value `None`.
It returns an empty dictionary.

توضیح

Subscription requires the requested key to exist, and `b` has no mapping in this dictionary, so lookup raises `KeyError`. It neither returns `None` nor inserts a default entry as a side effect.

توضیح

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