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# +=(_:_:)

Adds two values and stores the result in the left-hand-side variable.

```
static func += (lhs: inout UInt16, rhs: UInt16)
```

## Parameters

`lhs`

The first value to add.

`rhs`

The second value to add.

## Discussion

The sum of the two arguments must be representable in the arguments’
type. In the following example, the result of `21 + 120` is greater than
the maximum representable `Int8` value:

```
var x: Int8 = 21
x += 120
// Overflow error
```

> Note: Overflow checking is not performed in `-Ounchecked` builds.

---

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