def _write_fonts(self):

        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'})
                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
add fonts part to root
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/tablib-0.10.0/tablib/packages/openpyxl3/writer/styles.py/StyleWriter._write_fonts