# instances\_exist

### Description

`instance_exists` or `instances_exist` returns True if the case has at least one [instance](https://docs.atfinity.io/guides/glossary/instance) of the specified type(s). Like with other declarations an optional where clause is also supported.

### Example: Ontology and Role

```
instances_exist(Person, AccountHolder)
```

This will return True if there is at least one Person with the [role](https://docs.atfinity.io/guides/glossary/role) AccountHolder.

### Example: Ontology and Where-Clause

```
instance_exists(Person where self.first_name = 'Thorben')
```

This will return True if there is at least one Person with the `first_name` Thorben.