input: Write a python function to find the maximum index of an array's sub-array.
  assert findMaxIndex([2, 3, 4, 5, 7, 9, 11]) == 6
  assert findMaxIndex([1, 3, 5, 7, 9, 2, 0]) == 4
  assert findMaxIndex([10, 9, 8, 7, 6, 5, 4]) == 0
output: def findMaxIndex(arr):
      max_index = 0
      for i in range(1, len(arr)):
          if arr[i] > arr[max_index]:
              max_index = i
      return max_index