1 class C: 2 def f(self, x, y, z): 3 return z 4 5 class D: 6 def f(self, a, b, c): 7 return c 8 9 def pqr(obj): 10 return obj.f(1, 2, r=3) # no corresponding function 11 12 c = C() 13 d = D() 14 15 print pqr(c) # should fail