>>> class Master(object):
...     a = 'help'
...     def p(self):
...         print self.a
...
>>> class Child(Master):
...     a = 'help child'
...
>>> class MasterE(Master):
...     a = 'Master help'
...
>>> class ChildE(Child, MasterE):
...     def c(self):
...         print self.a
ChildEm().a
'Master help'