"Implementing your own version of laziness" makes it sound error-prone and difficult. In fact it's this pattern:

  def move(board, position, player):
    """
      board is a 11-character string which is 3 lengths of 3 of the characters
        X, O or _, separated by newlines
      turn is either X or O, depending on who moves
    """
    return board[:position] + player + board[position+1:]

  def getNextStates(board, player):
    spaces = [ i for i,c in enumerate(board) if c == '_' ]
    return [ move(board, i, player) for i in spaces ]

  >>> print board
  X_O
  _OX
  X_O 
  
  >>> for state in getNextStates(board, 'O'):
  ...   print state
  ...   print
  ... 
  XOO
  _OX
  X_O
 
  X_O
  OOX
  X_O
  
  X_O
  _OX
  XOO

I doubt most programmers exposed only to imperative programming would even notice that there was a pattern in what they were implementing, let alone identify it as laziness.