import collections
class __Helper(object):
    def __getitem__(self, ctor):
        return lambda: collections.defaultdict(lambda: ctor())
genericdefaultdict = __Helper()

if __name__ == '__main__':
    a = genericdefaultdict[int]()
    a[1] += 1
    print "a[1]=", a[1]
    
    b = genericdefaultdict[genericdefaultdict[int]]()
    b[1][2] += 12
    print "b[1][2]=", b[1][2]