سؤال 42

After `data = dict(a=1)` and `value = data.get("b", 9)`, what are `value` and the keys of `data`?

`value` is `None`, and only `a` remains a key.
`value` is 9, and only `a` remains a key.پاسخ درست
`value` is 9, and both `a` and `b` become keys.
The call raises `KeyError`, and the dictionary is unchanged.

توضیح

Because `b` is absent, `get` returns the supplied default 9, but it performs no assignment to the dictionary. Expecting a new key confuses a nonmutating lookup with methods that explicitly create missing entries.

توضیح

ادامهٔ این آزمون