# and then

### Description

When using `and then`, the second [expression](https://docs.atfinity.io/rule-language/expressions) is only evaluated after the first has evaluated to 'true'. That means that the [field](https://docs.atfinity.io/rule-language/operators/boolean-operators/broken-reference) in the second expression will not be asked before the first one is answered.

This is a good operator to use when a condition only needs to be evaluated under certain circumstances.

### Example

```
e is Entity
e.entity_type = trust 
and then
e.number_of_trust_founders > 0
```

This composed condition could be attached to a [document](https://docs.atfinity.io/guides/glossary/document) needed for trust founders. You only want to ask about the number of trust founders, if the document is actually about a trust.

That means you first determine the type of entity. This happens on line 2 of the example, where you want the system to check if the entity is a trust or not.

If it is, and only then, you want to ask how many founders the trust has. You wouldn't ask that, if the entity isn't a trust.

That's why `and then` is the operator to use here: only ask about the number of trust founders, after the first question on the entity type has been answered and evaluates to 'true'.