# |= operator

Source: https://ref.dm-lang.org/operator/vertequals

### Format
> `A |= B`

Set A equal to A | B. It is shorthand for A = A | B.

This is commonly used to turn on certain bitfields in a word.

```dm
usr.sight |= BLIND // turn on the blind bit
```

If A and B are lists, any items in B that are not already in A are added to A.

If A is an /icon or /matrix datum, the datum will be changed rather than creating a new one and re-assigning it to A.

### See also
- [&= operator](https://ref.dm-lang.org/operator/ampequals.md)
- [operators](https://ref.dm-lang.org/operator/index.md)
- [| operator](https://ref.dm-lang.org/operator/vert.md)