extern static void dispatch_sync_f(IntPtr queue, IntPtr context, dispatch_callback_t dispatch);
extern static void dispatch_queue_set_specific(IntPtr queue, /* const void* */ IntPtr key, /* void *_Nullable */ IntPtr context, dispatch_callback_t /* _Nullable */ destructor);
extern static void dispatch_after_f(/* dispath_time_t */ ulong time, IntPtr queue, IntPtr context, dispatch_callback_t dispatch);
static extern void dispatch_sync_f(IntPtr queue, IntPtr context, dispatch_callback_t dispatch);
extern static void dispatch_after_f (/* dispath_time_t */ ulong time, IntPtr queue, IntPtr context, dispatch_callback_t dispatch);
extern static void dispatch_barrier_async_f (IntPtr queue, IntPtr context, dispatch_callback_t dispatch);