+#include <objc/NSObject.h>
+
+// All methods of class Protocol are unavailable.
+// Use the functions in objc/runtime.h instead.
+
+__OSX_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0)
+@interface Protocol : NSObject
+@end
+
+
+#else
+
+#include <objc/Object.h>
+
+__OSX_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0)