old_contents: class TableTop(object):
      
      def __init__(self):
          self.board = [[0,0,0],[0,0,0],[0,0,0]]
  
new_contents: class TableTop(object):
      
      def __init__(self):
          self.board = [0,0,0,0,0,0,0,0,0]
  
subject: change TableTop.board to be a flat list