def decode_list(self, data_type, obj):
        """
        The data_type argument must be a List.
        See json_compat_obj_decode() for argument descriptions.
        """
        if not isinstance(obj, list):
            raise bv.ValidationError(
                'expected list, got %s' % bv.generic_type_name(obj))
        return [
            self.json_compat_obj_decode_helper(data_type.item_validator, item)
            for item in obj]
The data_type argument must be a List.
        See json_compat_obj_decode() for argument descriptions.