subtype Effect Handler
fun <F : Any, E> subtypeEffectHandler(executionPolicy: ExecutionPolicy, block: SubtypeEffectHandlerBuilder<F, E>.() -> Unit): FlowTransformer<F, E>
fun <F : Any, E> subtypeEffectHandler(block: SubtypeEffectHandlerBuilder<F, E>.() -> Unit): FlowTransformer<F, E>