input: Write a python function to find the maximum element in a 2D array.
  assert maxElement2DArray([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) == 9
  assert maxElement2DArray([[10, 20, 30], [5, 15, 25], [0, 50, 100]]) == 100
  assert maxElement2DArray([[3, 3, 3], [3, 3, 3], [3, 3, 3]]) == 3
output: def maxElement2DArray(arr):
      return max(max(row) for row in arr)