docs: def set_pos(self, pos, check=False):
          '''Set a chess'''
          self.validate_pos(pos)
          x, y = pos
          user = self.get_player()
          self.history[self._game_round] = copy.deepcopy(self.pos)
          self.pos[x][y] = user
          pos_str = self._cal_key(pos)
          self._pos_dict[pos_str] = user
          self._user_pos_dict[user].append(pos)
          self._game_round += 1
          if check:
              winning = self.check_win_by_step(x, y, user)
              return winning
          else:
              return (x, y)