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I couldn't find a test for it neither in https://github.com/tc39/test262/blob/main/test/built-ins/Array/prototype/Symbol.unscopables nor in https://github.com/tc39/test262/tree/main/test/built-ins/Array/prototype/at.
I can open a PR, but should I add it to https://github.com/tc39/test262/blob/main/test/built-ins/Array/prototype/Symbol.unscopables/value.js or to a new file (since it needs a new feature flag)?