How to use the tablib.packages.openpyxl3.shared.xmltools.SubElement function in tablib

def _write_fonts(self):
        """ add fonts part to root
            return {font.crc => index}
        """

        fonts = SubElement(self._root, 'fonts')
        
        # default
        font_node = SubElement(fonts, 'font')
        SubElement(font_node, 'sz', {'val':'11'})
        SubElement(font_node, 'color', {'theme':'1'})
        SubElement(font_node, 'name', {'val':'Calibri'})
        SubElement(font_node, 'family', {'val':'2'})
        SubElement(font_node, 'scheme', {'val':'minor'})
        
        # others
        table = {}
        index = 1
        for st in self._style_list:
            if hash(st.font) != hash(style.DEFAULTS.font) and hash(st.font) not in table:
                table[hash(st.font)] = str(index)
                font_node = SubElement(fonts, 'font')
                SubElement(font_node, 'sz', {'val':str(st.font.size)})
                SubElement(font_node, 'color', {'rgb':str(st.font.color.index)})
                SubElement(font_node, 'name', {'val':st.font.name})

def _write_cell_xfs(self, number_format_table, fonts_table, fills_table, borders_table):
        """ write styles combinations based on ids found in tables """
        
        # writing the cellXfs
        cell_xfs = SubElement(self._root, 'cellXfs', 
            {'count':'%d' % (len(self._style_list) + 1)})
        
        # default
        def _get_default_vals():
            return dict(numFmtId='0', fontId='0', fillId='0', 
                xfId='0', borderId='0')
        
        SubElement(cell_xfs, 'xf', _get_default_vals())
        
        for st in self._style_list:
            vals = _get_default_vals()
            
            if hash(st.font) != hash(style.DEFAULTS.font):
                vals['fontId'] = fonts_table[hash(st.font)]
                vals['applyFont'] = '1'

# others
        table = {}
        index = 1
        for st in self._style_list:
            if hash(st.font) != hash(style.DEFAULTS.font) and hash(st.font) not in table:
                table[hash(st.font)] = str(index)
                font_node = SubElement(fonts, 'font')
                SubElement(font_node, 'sz', {'val':str(st.font.size)})
                SubElement(font_node, 'color', {'rgb':str(st.font.color.index)})
                SubElement(font_node, 'name', {'val':st.font.name})
                SubElement(font_node, 'family', {'val':'2'})
                SubElement(font_node, 'scheme', {'val':'minor'})
                if st.font.bold:
                    SubElement(font_node, 'b')
                if st.font.italic:
                    SubElement(font_node, 'i')
                index += 1
                
        fonts.attrib["count"] = str(index)
        return table

def _write_cell_style_xfs(self):
        cell_style_xfs = SubElement(self._root, 'cellStyleXfs', {'count':'1'})
        xf = SubElement(cell_style_xfs, 'xf', 
            {'numFmtId':"0", 'fontId':"0", 'fillId':"0", 'borderId':"0"})

for number_format in number_format_list:

            if number_format.is_builtin():
                btin = number_format.builtin_format_id(number_format.format_code)
                number_format_table[number_format] = btin
            else:
                number_format_table[number_format] = num_fmt_id + num_fmt_offset
                num_fmt_offset += 1
                exceptions_list.append(number_format)

        num_fmts = SubElement(self._root, 'numFmts', 
            {'count':'%d' % len(exceptions_list)})

        for number_format in exceptions_list :
            SubElement(num_fmts, 'numFmt', 
                {'numFmtId':'%d' % number_format_table[number_format],
                'formatCode':'%s' % number_format.format_code}) 
        
        return number_format_table

def _write_dxfs(self):
        dxfs = SubElement(self._root, 'dxfs', {'count':'0'})

def _write_fonts(self):
        """ add fonts part to root
            return {font.crc => index}
        """

        fonts = SubElement(self._root, 'fonts')
        
        # default
        font_node = SubElement(fonts, 'font')
        SubElement(font_node, 'sz', {'val':'11'})
        SubElement(font_node, 'color', {'theme':'1'})
        SubElement(font_node, 'name', {'val':'Calibri'})
        SubElement(font_node, 'family', {'val':'2'})
        SubElement(font_node, 'scheme', {'val':'minor'})
        
        # others
        table = {}
        index = 1
        for st in self._style_list:
            if hash(st.font) != hash(style.DEFAULTS.font) and hash(st.font) not in table:
                table[hash(st.font)] = str(index)
                font_node = SubElement(fonts, 'font')
                SubElement(font_node, 'sz', {'val':str(st.font.size)})
                SubElement(font_node, 'color', {'rgb':str(st.font.color.index)})
                SubElement(font_node, 'name', {'val':st.font.name})
                SubElement(font_node, 'family', {'val':'2'})

def _write_cell_style_xfs(self):
        cell_style_xfs = SubElement(self._root, 'cellStyleXfs', {'count':'1'})
        xf = SubElement(cell_style_xfs, 'xf', 
            {'numFmtId':"0", 'fontId':"0", 'fillId':"0", 'borderId':"0"})

def _write_borders(self):
        borders = SubElement(self._root, 'borders')

        # default
        border = SubElement(borders, 'border')
        SubElement(border, 'left')
        SubElement(border, 'right')
        SubElement(border, 'top')
        SubElement(border, 'bottom')
        SubElement(border, 'diagonal')
        
        # others
        table = {}
        index = 1
        for st in self._style_list:
            if hash(st.borders) != hash(style.DEFAULTS.borders) and hash(st.borders) not in table:
                table[hash(st.borders)] = str(index)
                border = SubElement(borders, 'border')
                # caution: respect this order
                for side in ('left','right','top','bottom','diagonal'):
                    obj = getattr(st.borders, side)
                    node = SubElement(border, side, {'style':obj.border_style})
                    SubElement(node, 'color', {'rgb':str(obj.color.index)})
                index += 1

# default
        border = SubElement(borders, 'border')
        SubElement(border, 'left')
        SubElement(border, 'right')
        SubElement(border, 'top')
        SubElement(border, 'bottom')
        SubElement(border, 'diagonal')
        
        # others
        table = {}
        index = 1
        for st in self._style_list:
            if hash(st.borders) != hash(style.DEFAULTS.borders) and hash(st.borders) not in table:
                table[hash(st.borders)] = str(index)
                border = SubElement(borders, 'border')
                # caution: respect this order
                for side in ('left','right','top','bottom','diagonal'):
                    obj = getattr(st.borders, side)
                    node = SubElement(border, side, {'style':obj.border_style})
                    SubElement(node, 'color', {'rgb':str(obj.color.index)})
                index += 1
        
        borders.attrib["count"] = str(index)
        return table