1@interface Foo 2@end 3 4@interface Foo(Top) 5-(void)top; 6@end 7 8@interface Foo(Top2) 9-(void)top2; 10@end 11 12@interface Foo(Top3) 13-(void)top3; 14@end 15 16@protocol P1 17@end 18 19@protocol P2 20@end 21 22@protocol P3, P4; 23 24