code: static IDataModel toDataModel(final Workbook book, final ICellAddress address) {
          if (book == null || address == null) { return null; }
          if (address instanceof A1RangeAddress) { throw new CalculationEngineException("A1RangeAddress is not supported, only one cell can be converted to DataModel."); }
          
          Sheet s = book.getSheetAt(0); /* TODO: only one sheet is supported */
          Row r = s.getRow(address.a1Address().row());
          if (r == null) { return null; }
          Cell c = r.getCell(address.a1Address().column());
          if (c == null || CELL_TYPE_FORMULA != c.getCellType()) { return null; }
  
          return createDataModelFromCell(s, create((XSSFWorkbook) book), fromRowColumn(c.getRowIndex(), c.getColumnIndex()));
      }
docs: Extracts {@link IDataModel} from {@link Workbook} at given {@link ICellAddress}.
  Useful for formula. If given {@link ICellAddress} contains formula it can be parsed.
  Based on this parsed information a new {@link IDataModel} might be created.