input: Write a function to calculate the average of the elements in a 2-dimensional array. The function should return the average rounded to two decimal places. If the array is empty, return 0.00.
  def averageMatrix(matrix):
      if not matrix:
          return 0.00
      sum = 0
      for row in matrix:
          for e in row:
              sum += e
      return round(sum / (len(matrix) * len(matrix[0])), 2)
  
  a = [[3, 2, 6],
       [8, 5, 9],
       [4, 7, 1]]
  
  assert averageMatrix(a) == 4.77
  assert averageMatrix([]) == 0.00
  assert averageMatrix([[1,2],[3,4]]) == 2.50
output: def averageMatrix(matrix):
      if not matrix:
          return 0.00
      sum = 0
      for row in matrix:
          for e in row:
              sum += e
      return round(sum / (len(matrix) * len(matrix[0])), 2)