input: Write a function to calculate the average of the elements in a 2-dimensional array. The function should return the average value. If the input array is empty, it should return 0.
  
  def averageMatrix(matrix):
      if not matrix:
          return 0
      sum = 0
      count = 0
      for row in matrix:
          for e in row:
              sum += e
              count += 1
      return sum / count
  
  a = [[3,2,6],
       [8,5,9],
       [4,7,1]]
  
  print(averageMatrix(a)) # 4.77
output: def averageMatrix(matrix):
      if not matrix:
          return 0
      sum = 0
      count = 0
      for row in matrix:
          for e in row:
              sum += e
              count += 1
      return sum / count