docs: def dims_knight(self, move):
      '''Knight on the rim is dim'''
      if self.board.piece_type_at(move.from_square) == chess.KNIGHT:
        rim = SquareSet(
            chess.BB_RANK_1 | \
            chess.BB_RANK_8 | \
            chess.BB_FILE_A | \
            chess.BB_FILE_H)
        return move.to_square in rim