gistfile1.txt

class DefaultDict(dict):
    def __new__(cls, default_value):
        new_instance = super(DefaultDict, cls).__new__(cls, default_value)
        return new_instance
    def __init__(self, default_value):
        self.default_value = default_value
        super(DefaultDict, self).__init__()
        
    def __getitem__(self, item):
        if item not in self:
            self[item] = self.default_value
        return self.default_value

    def __repr__(self):
        return 'DefaultDict <default %s> %s' % (self.default_value, dict.__repr__(self))