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function listOf(...init) {    let array = init || [];    let proxy = new Proxy(array, {        get(target, prop) {            prop = prop.split(',').map(n => parseInt(n, 10));
            switch (prop.length) {                case 1:                    if (!isNaN(prop)) {                        if (prop < 0) {                            prop += target.length;                        }                    }                    return target[prop];                case 2:                case 3:                    return target.slice(...prop);                default:                    throw new Error('invalid array access');            }        }    });    return proxy;}