flattenArr

flattenArr(arr):
  # base case
	## how to check if a variable is an array http://stackoverflow.com/questions/767486/how-do-you-check-if-a-variable-is-an-array-in-javascript
	if (arr.constructor != Array) {
		return [arr];
	}
  # recursion
	else {
		foundElements = []
	  for (var i = 0; i < arr.size; i++) {
       elts = flattenArr(arr[i])
       foundElements  = foundElements.concat(elts)
    }
    return foundElements;
}