input: from typing import List
  
  def averageMatrix(matrix: List[List[int]]) -> float:
      """ Calculates the average of the elements in a 2-dimensional array.
      >>> averageMatrix([[3,2,6],
                        [8,5,9],
                        [4,7,1]])
      4.77
      """
      sum = 0
      for row in matrix:
          for e in row:
              sum += e
  
      return round(sum / (len(matrix) * len(matrix[0])), 2)
  
  a = [[3,2,6],
       [8,5,9],
       [4,7,1]]
  
  print(averageMatrix(a)) # 4.77
output:     sum = 0
      for row in matrix:
          for e in row:
              sum += e
  
      return round(sum / (len(matrix) * len(matrix[0])), 2)