code: public RecordId insertIntoDeletedSlot() {
  		RecordId nds = getNextDeletedSlotId();
  		// Important: Erase the free chain information.
  		// If we didn't do this, it would crash when
  		// a tx try to set a VARCHAR at this position
  		// since the getVal would get negative size.
  		setNextDeletedSlotId(new RecordId(new BlockId("", 0), 0));
  		Constant flag = INUSE_CONST;
  		setVal(currentPos(), flag);
  		return nds;
  	}
docs: Inserts a new, blank record into this deleted slot and return the record
  id of the next one.
  
  @return the record id of the next deleted slot