input: Write a function to calculate the average of the elements in a 2-dimensional array. The function should return the average as a floating-point number.
  
  def averageMatrix(matrix):
   sum = 0
   for row in matrix:
    for e in row:
     sum += e
  
   return sum / (len(matrix) * len(matrix[0]))
  
  a = [[3, 2, 6],
       [8, 5, 9],
       [4, 7, 1]]
  
  assert averageMatrix(a) == 4.77
  assert averageMatrix([[1, 2], [3, 4]]) == 2.5
  assert averageMatrix([]) == 0.0
  assert averageMatrix([[5]]) == 5.0
  assert averageMatrix([[8, 2], [3, 4]]) == 4.25
output: def averageMatrix(matrix):
      if not matrix:
          return 0.0
      sum = 0
      count = 0
      for row in matrix:
          for e in row:
              sum += e
              count += 1
      return sum / count