class A(object):
    def do_your_stuff(self):
        # do stuff with self for A
        print "a"
    
class B(A):
    def do_your_stuff(self):
        next_class = self.find_out_whos_next()
        #print next_class
        next_class.do_your_stuff(self)
        print "b"

    def find_out_whos_next(self):
        l = self.supertypes_list
        mypos = l.index(B)
        return l[mypos+1] 
    
class C(A):
    def do_your_stuff(self):
        next_class = self.find_out_whos_next()
        #print next_class
        next_class.do_your_stuff(self)
        print "c"

    def find_out_whos_next(self):
        l = self.supertypes_list
        mypos = l.index(C)
        return l[mypos+1] 

class D(B,C):
    def do_your_stuff(self):
        next_class = self.find_out_whos_next()
        next_class.do_your_stuff(self)
        print "d"

    def find_out_whos_next(self):
        l = self.supertypes_list
        mypos = l.index(D)
        return l[mypos+1] 


B.supertypes_list = [B,A]
C.supertypes_list = [C,A]
D.supertypes_list = [D,B,C,A]



if __name__ == "__main__" :

    foobar = D()
    foobar.do_your_stuff()