fun <T> SpecBody.checkNarrowingNullableAssertion(description: String, act: (IAssertionPlantNullable<T>.() -> Unit) -> Unit, immediate: IAssertionPlantNullable<T>.() -> Unit, lazy: IAssertionPlantNullable<T>.() -> Unit, vararg otherMethods: Pair<String, IAssertionPlantNullable<T>.() -> Unit>): Unit