这段代码是什么意思?
var className = (0, _classnames2["default"])((_classNames = {},
_defineProperty(_classNames, props.className, !!props.className),
_defineProperty(_classNames, prefixCls, 1),
_defineProperty(_classNames, prefixCls + '-checked', checked),
_defineProperty(_classNames, prefixCls + '-checked-' + checked, !!checked),
_defineProperty(_classNames, prefixCls + '-focused', state.focus),
_defineProperty(_classNames, prefixCls + '-disabled', props.disabled),
_classNames)
);
括号里面的0代表什么?