input: Write a function to calculate the average of the elements in a 2-dimensional array by summing all the elements and then dividing by the total number of elements. If the given array is empty, return 0.
  def averageMatrix(matrix):
      if not matrix:
          return 0
      total_sum = 0
      count = 0
      for row in matrix:
          for element in row:
              total_sum += element
              count += 1
      return total_sum / count
  
  assert averageMatrix([[3,2,6], [8,5,9], [4,7,1]]) == 5.0
  assert averageMatrix([[1,2], [3,4]]) == 2.5
  assert averageMatrix([[0,0,0], [0,0,0]]) == 0
  assert averageMatrix([[]]) == 0
  assert averageMatrix([]) == 0
output: def averageMatrix(matrix):
      if not matrix:
          return 0
      total_sum = 0
      count = 0
      for row in matrix:
          for element in row:
              total_sum += element
              count += 1
      return total_sum / count