function steamrollArray(arr) {
  var madeOne=[];
  function deepNesting(arg){
    if (Array.isArray(arg))
    {
      arg.forEach(function (element) {
        deepNesting(element);
      });
    } else {
      madeOne.push(arg);
    }
  }
  arr.forEach(deepNesting);
  console.log(arr);
  console.log(madeOne);
  return madeOne;
}