def _register_configs(configs, to_register):
    """ param dict configs: pair param_name(str) : param_configs(dict)
        param to_register: pair param_name(str) : param_configs(dict) or attr(str) : attr_value(object)
    """
    _configs = {}
    for identifier, attr_value in to_register.items():
        assert isinstance(identifier, str), KeyError()
        if identifier in configs:
            _configs[identifier] = attr_value
        else:
            for config in configs.values():
                config[identifier] = attr_value
    for identifier, attr_value in _configs.items():
        configs[identifier].update(attr_value)
