func (f *File) SetCellRichText(sheet, cell string, runs []RichTextRun) error {
	ws, err := f.workSheetReader(sheet)
	if err != nil {
		return err
	}
	cellData, col, _, err := f.prepareCell(ws, sheet, cell)
	if err != nil {
		return err
	}
	cellData.S = f.prepareCellStyle(ws, col, cellData.S)
	si := xlsxSI{}
	sst := f.sharedStringsReader()
	textRuns := []xlsxR{}
	for _, textRun := range runs {
		run := xlsxR{T: &xlsxT{Val: textRun.Text}}
		if strings.ContainsAny(textRun.Text, "\r\n ") {
			run.T.Space = xml.Attr{Name: xml.Name{Space: NameSpaceXML, Local: "space"}, Value: "preserve"}
		}
		fnt := textRun.Font
		if fnt != nil {
			rpr := xlsxRPr{}
			if fnt.Bold {
				rpr.B = " "
			}
			if fnt.Italic {
				rpr.I = " "
			}
			if fnt.Strike {
				rpr.Strike = " "
			}
			if fnt.Underline != "" {
				rpr.U = &attrValString{Val: &fnt.Underline}
			}
			if fnt.Family != "" {
				rpr.RFont = &attrValString{Val: &fnt.Family}
			}
			if fnt.Size > 0.0 {
				rpr.Sz = &attrValFloat{Val: &fnt.Size}
			}
			if fnt.Color != "" {
				rpr.Color = &xlsxColor{RGB: getPaletteColor(fnt.Color)}
			}
			run.RPr = &rpr
		}
		textRuns = append(textRuns, run)
	}
	si.R = textRuns
	if cellData.V == "" {
		sst.SI = append(sst.SI, si)
		sst.Count++
		sst.UniqueCount++
		cellData.T, cellData.V = "s", strconv.Itoa(len(sst.SI)-1)
	} else {
		siIndex, err := strconv.Atoi(cellData.V)
		if nil != err {
			return err
		}

		sst.SI[siIndex] = si
	}
         // NOTICE: this is bug
	// sst.SI = append(sst.SI, si)

	return err
}

for idx, strItem := range sst.SI {
    if reflect.DeepEqual(strItem, si) {
        cellData.T, cellData.V = "s", strconv.Itoa(idx)
        return err
    }
}