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# reserveCapacity(_:)

Ensure that the array has capacity to store the specified number of
elements, by growing its storage buffer if necessary.

```
mutating func reserveCapacity(_ n: Int)
```

## Discussion

If `capacity < n`, then this operation reallocates the unique array’s
storage to grow it; on return, the array’s capacity becomes `n`.
Otherwise the array is left as is.

> Complexity: O(`count`)

---

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