Common
```kotlin
interface Interval
```
Common content of individual intervals in `item` DSL of lazy layouts.
Note: this class is a part of [LazyLayout](/jetpack-compose/androidx.compose.foundation/foundation/composable-functions/LazyLayout) harness that allows for building custom lazy
layouts. LazyLayout and all corresponding APIs are still under development and are subject to
change.
## Properties
Common
```kotlin
val key: ((index: Int) -> Any)?
```
Returns item key based on a local index for the current interval.
Common
```kotlin
val type: ((index: Int) -> Any?)
```
Returns item type based on a local index for the current interval.