class A():
   def __init__(self): self.x = 10
   def foo(self): print(self.x)
 
class B(A,object):
  def foo(self):
    super(B, self).foo()
    self.x = 50
    super(B, self).foo()
 
B().foo()

class C(A):
   def foo(self):
     A.foo(self)
     self.x = 50
     A.foo(self)

C().foo()