def setdefault(cls, key, default, deserialize_json=False):
        """
        
        """
        obj = Variable.get(key, default_var=None,
                           deserialize_json=deserialize_json)
        if obj is None:
            if default is not None:
                Variable.set(key, default, serialize_json=deserialize_json)
                return default
            else:
                raise ValueError('Default Value must be set')
        else:
            return obj