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# replaceUnsafeMutableBytes(_:)

Replace the buffer’s contents synchronously on the CPU.

```
final func replaceUnsafeMutableBytes(_ callback: (UnsafeMutableRawBufferPointer) -> Void)
```

## Discussion

The buffer’s contents are unspecified, and it is the caller’s responsibility
to populate the buffer with valid data.
The buffer provided is only valid for the lifetime of the callback.

---

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