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# Progress.PublishingHandler

A block that the system calls when an observed progress object matches the subscription.

```
typealias PublishingHandler = @Sendable (Progress) -> Progress.UnpublishingHandler?
```

## Parameters

`progress`

The proxy to the observed progress object.

## Return Value

An optional block that the system invokes when the observed progress object invokes [`unpublish()`](/documentation/Foundation/Progress/unpublish()), the publishing process terminates, or you invoke [`removeSubscriber(_:)`](/documentation/Foundation/Progress/removeSubscriber(_:)).

---

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