# UNION\_OF\_ANY

### Description

`UNION_OF_ANY` is the flexible counterpart of [`UNION`](https://docs.atfinity.io/rule-language/operators/list-operators/union).

It creates a combined set of all the lists you provide. Duplicates in the new list will be removed. 

If a value or list is not available:

* `UNION_OF_ANY` simply ignores it and combines what is available.
* `UNION`, before returning a result, will ask users to go back and provide the missing list.

### Examples

```
p is Person
UNION_OF_ANY(
    p.countries_lived_in, 
    p.countries_banned_from
)
```

A person in a case has lived in Germany, Switzerland, and Singapore. Being a fine, law abiding citizen, the person has not been banned from any countries.

The above [expression](https://docs.atfinity.io/rule-language/expressions) will result in the list

\[de, ch, sg]<br>

Because `UNION_OF_ANY` is used, the request for ‘countries banned from’ is ignored, because there are none for this person.

Would you have used `UNION` instead, the system would have alerted you to provide one or more countries the person is banned from before giving you the combined list.\ <br>