#define x y
#define x z

#define abc 123
#define abc() 123

#define foo() bar
#define foo(x) bar

#define bar() baz
#define bar baz

#define biff(a,b) a+b
#define biff(a,b,c) a+b

#define oper(a,b) a+b
#define oper(a,b) a*b