@constructor

@param  {Array}  arr     (optional) Array to stream
@param  {Object} options {duplex: false}
function ArrayStream(arr, options) {
    var self = this;
    this._reading = false;
    this._closing = false;
    this._index = 0;
    options = options || {};
    this._duplex = options.duplex || false;

    this.set(arr);

    Duplex.call(this, {
        objectMode: true,
        highWaterMark: options.highWaterMark || Math.pow(2, 10)
    });
}