compare
fun compareAndSetFiberCaptureFunction(fiberKind: FiberDescriptor.FiberKind, oldValue: (A_Fiber) -> Unit?, newValue: (A_Fiber) -> Unit?): Boolean
Attempt to write the newValue into the specified newFiberHandlers, but only if it currently contains oldValue. Answer whether it wos successful. If it was not successful due to the oldValue not being the current value, make no change and answer false.