The default Ruby Array class allows inserting into an array at an that doesn't exist. For example, a user may do this `array[2938] = 48` when the array contains only about six (6) elements. This causes the the array to now contain 2,000 plus of nil elements. The goal is to avoid this by intelligently appending to the end of the array when such action is performed. Also, invalid negative indexes will throw an `IndexError` exception as usual. There are other useful methods added on top of the Array class for common tasks.