annotation class ExperimentalContracts

This marker distinguishes the experimental contract declaration API and is used to opt-in for that feature when declaring contracts of user functions.

Any usage of a declaration annotated with @ExperimentalContracts must be accepted either by annotating that usage with the OptIn annotation, e.g. @OptIn(ExperimentalContracts::class), or by using the compiler argument -Xopt-in=kotlin.contracts.ExperimentalContracts.