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