code: func (pos *Position) String() string {
  	b := pos.board.String()
  	t := pos.turn.String()
  	c := pos.castleRights.String()
  	sq := "-"
  	if pos.enPassantSquare != NoSquare {
  		sq = pos.enPassantSquare.String()
  	}
  	return fmt.Sprintf("%s %s %s %s %d %d", b, t, c, sq, pos.halfMoveClock, pos.moveCount)
  }
docs: // String implements the fmt.Stringer interface and returns a
  // string with the FEN format: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1