input: Write a function to calculate the average of the elements in a 2-dimensional array. The function should return the average value as a floating-point number. If the input matrix is empty, the function should 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
  
  a = [[3, 2, 6], [8, 5, 9], [4, 7, 1]]
  print(averageMatrix(a)) # 4.777777777777778
  
  assert averageMatrix([[1, 2], [3, 4]]) == 2.5
  assert averageMatrix([[10, 20, 30], [40, 50, 60]]) == 35.0
  assert averageMatrix([[1], [2], [3], [4]]) == 2.5
  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