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# next(isolation:)

Produces the next element in the filter sequence.

```
mutating func next(isolation actor: isolated (any Actor)?) async throws -> Base.Element?
```

## Discussion

This iterator calls `next(isolation:)` on its base iterator; if this
call returns `nil`, `next(isolation:)` returns nil. Otherwise, `next()`
evaluates the result with the `predicate` closure. If the closure
returns `true`, `next(isolation:)` returns the received element;
otherwise it awaits the next element from the base iterator. If calling
the closure throws an error, the sequence ends and `next(isolation:)`
rethrows the error.

---

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