input: def averageMatrix(matrix):
      """Calculate the average of all the elements in a 2-dimensional array.
      >>> averageMatrix([[3,2,6],[8,5,9],[4,7,1]])
      4.77
      """
      total_sum = 0
      for row in matrix:
          for element in row:
              total_sum += element
      
      return total_sum / (len(matrix) * len(matrix[0]))
output:     total_sum = 0
      count = 0
      for row in matrix:
          for element in row:
              total_sum += element
              count += 1
      
      return round(total_sum / count, 2)