input: Write a python function to find the maximum number in a 2D array and its index.
  assert max_2d_array([[1, 2, 3], [4, 5, 6], [7, 8, 9]]) == (9, (2, 2))
  assert max_2d_array([[10, 20, 30], [5, 15, 25], [1, 2, 3]]) == (30, (0, 2))
  assert max_2d_array([[11, 22], [33, 44], [55, 66]]) == (66, (2, 1))
output: def max_2d_array(arr):
      max_value = float('-inf')
      max_index = (-1, -1)
      
      for i in range(len(arr)):
          for j in range(len(arr[i])):
              if arr[i][j] > max_value:
                  max_value = arr[i][j]
                  max_index = (i, j)
      
      return (max_value, max_index)