docs: function parse_Theme(blob, length, opts) {
  	var end = blob.l + length;
  	var dwThemeVersion = blob.read_shift(4);
  	if(dwThemeVersion === 124226) return;
  	if(!opts.cellStyles || !jszip) { blob.l = end; return; }
  	var data = blob.slice(blob.l);
  	blob.l = end;
  	var zip; try { zip = new jszip(data); } catch(e) { return; }
  	var themeXML = getzipstr(zip, "theme/theme/theme1.xml", true);
  	if(!themeXML) return;
  	return parse_theme_xml(themeXML, opts);
  }