1 class C: 2 a = 1 3 b = 2 4 5 class D(C): 6 pass 7 8 def f(): 9 C.a = 3 # only changes C.a, not D.a 10 11 print C.a # 1 12 print D.a # 1 13 print C.b # 2 14 print D.b # 2 15 16 f() 17 18 print C.a # 3 19 print D.a # 1