input: Write a function to calculate the average of the elements in a 2-dimensional array. The function should return the average value rounded to two decimal places. If the input matrix is empty, the function should return 0.
  
  def averageMatrix(matrix):
      if not matrix:
          return 0
      sum = 0
      count = 0
      for row in matrix:
          for e in row:
              sum += e
              count += 1
      return round(sum / count, 2)
  
  a = [[3, 2, 6],
       [8, 5, 9],
       [4, 7, 1]]
  
  assert averageMatrix(a) == 5.22
  assert averageMatrix([[]]) == 0
  assert averageMatrix([]) == 0
  assert averageMatrix([[1, 2, 3], [4, 5, 6]]) == 3.5
  assert averageMatrix([[10, 20], [30, 40]]) == 25.0
output: def averageMatrix(matrix):
      if not matrix:
          return 0
      sum = 0
      count = 0
      for row in matrix:
          for e in row:
              sum += e
              count += 1
      return round(sum / count, 2)