input: Write a python function to reverse an array in-place.
  assert reverseArray([1, 2, 3, 4, 5]) == [5, 4, 3, 2, 1]
  assert reverseArray([10, 20, 30, 40, 50]) == [50, 40, 30, 20, 10]
  assert reverseArray([7, 9, 11, 13, 15]) == [15, 13, 11, 9, 7]
output: def reverseArray(arr):
      left, right = 0, len(arr) - 1
      while left < right:
          arr[left], arr[right] = arr[right], arr[left]
          left += 1
          right -= 1
      return arr