input: Write a function to calculate the average of the elements in a 2-dimensional array. If the array is empty, it should return 0. Otherwise, it should return the calculated average value.
  
  def averageMatrix(matrix):
      if not matrix:
          return 0
      sum = 0
      for row in matrix:
          for e in row:
              sum += e
      return sum / (len(matrix) * len(matrix[0]))
  
  assert averageMatrix([[3,2,6], [8,5,9], [4,7,1]]) == 5.0
  assert averageMatrix([]) == 0
  assert averageMatrix([[1,1,1], [1,1,1], [1,1,1]]) == 1.0
  assert averageMatrix([[10,20], [30,40]]) == 25.0
  assert averageMatrix([[9,8], [7,6]]) == 7.5
output: def averageMatrix(matrix):
      if not matrix:
          return 0
      sum = 0
      for row in matrix:
          for e in row:
              sum += e
      return sum / (len(matrix) * len(matrix[0]))