input: Write a function to calculate the average of the elements in a 2-dimensional array. The function should iterate through each element in the array, sum them up, and then divide by the total number of elements. The function should return the average as a float.
  
  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],[4,5,6]]) == 3.5
  assert averageMatrix([[0,0],[0,0]]) == 0
  assert averageMatrix([[1,1],[1,1]]) == 1
  assert averageMatrix([[2]]) == 2
output: def averageMatrix(matrix):
   sum = 0
   for row in matrix:
    for e in row:
     sum += e
   return sum / (len(matrix) * len(matrix[0]))