docs: public void addCell(String content) {
      content = content.trim();
      if (content.startsWith("=")) {
        //Logger.debug("Table.addCell: function found.");
        if (null == functionOccurences) {
          functionOccurences = new ArrayList();
        }
        functionOccurences.add(new int[]{indexCol, indexRow});
        // function
      }
      currentRow.add(content);
      indexCol++;
    }