input: Write a function to calculate the average of the elements in a 2-dimensional array. If the array is empty, return 0.
  
  def averageMatrix(matrix):
      if not matrix:
          return 0
      
      total_sum = 0
      total_elements = 0
      
      for row in matrix:
          for element in row:
              total_sum += element
              total_elements += 1
      
      return total_sum / total_elements
  
  a = [[3,2,6],
       [8,5,9],
       [4,7,1]]
  
  assert averageMatrix(a) == 4.77
  assert averageMatrix([]) == 0
  assert averageMatrix([[1, 2], [3, 4]]) == 2.5
output: def averageMatrix(matrix):
      if not matrix:
          return 0
      
      total_sum = 0
      total_elements = 0
      
      for row in matrix:
          for element in row:
              total_sum += element
              total_elements += 1
      
      return total_sum / total_elements