let arr = [0];

function cloneLine() {
    arr.forEach(function (element) {
        agent.setItem(element, 1, 1);
        agent.place(FORWARD);
        agent.move(RIGHT, 1);
    });
}

player.onChat("13-1", function () {
    arr = [Block.OakFence,
           Block.AcaciaFence,
           Block.AcaciaFence,
           Block.DarkOakFence,
           Block.OakFence];

    cloneLine();
});