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# append(buffer:deallocator:flags:)

Adds a sliced memory block to a block buffer with a custom deallocator.

```
func append(buffer: Slice<UnsafeMutableRawBufferPointer>, deallocator: @escaping CMBlockBuffer.CustomBlockDeallocator, flags: CMBlockBuffer.Flags = []) throws
```

## Parameters

`buffer`

A block of memory to hold buffered data.

`deallocator`

An object that deallocates a memory block.

`flags`

Feature and control flags.

---

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