_sheet_from_list_of_lists(data) {
    const range = {s: {c: 10000000, r: 10000000}, e: {c: 0, r: 0}};
    const ws = {};

    function datenum(v, date1904) {
      const epoch = Date.parse(date1904 ? v + 1462 : v);
      return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);
    }

    data.forEach((row, idxRow) => {
      row.forEach((v, idxCol) => {
        if (v === null) return;

        if (range.s.r > idxRow) range.s.r = idxRow;
        if (range.s.c > idxCol) range.s.c = idxCol;
        if (range.e.r < idxRow) range.e.r = idxRow;
        if (range.e.c < idxCol) range.e.c = idxCol;

        const cell = {v};
        throw new Error('Sheet not yet implemented');
        // const cell_ref = XLSX.utils.encode_cell({c: idxCol, r: idxRow}); TODO

        if (typeof cell.v === 'number')
          cell.t = 'n';
        else if (cell.v instanceof Date) {
          cell.t = 'n'; cell.z = XLSX.SSF._table[14];
          cell.v = datenum(cell.v);
        } else
          cell.t = 's';

        ws[cell_ref] = cell;
      });
    });

    // if (range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range); TODO

    return ws;
  }
Get a Sheet object's content from a List of Lists
As inspiration: view-source:http://sheetjs.com/demos/writexlsx.html

@param data
@private