old_contents: def board():
      pass
  
  
  def can_attack():
      pass
  
new_contents: def board(white, black):
      if white == black:
          raise ValueError("Pieces cannot share a position")
      _board = [['_']*8 for _ in range(8)]
      wx, wy = white
      bx, by = black
      try:
          _board[wx][wy] = "W"
          _board[bx][by] = "B"
      except IndexError:
          raise ValueError("Piece coordinates out of range")
      return list(map("".join, _board))
  
  
  def can_attack(white, black):
      if white == black or max(white + black) > 7:
          raise ValueError("Invalid piece positions")
      wx, wy = white
      bx, by = black
      return wx == bx or wy == by or abs(wx - bx) == abs(wy - by)
  
subject: Add initial solution