function createBar(data, opt, symbolMeta, isUpdate) {
    // bar is the main element for each data.
    var bar = new Group();
    // bundle is used for location and clip.
    var bundle = new Group();
    bar.add(bundle);
    bar.__pictorialBundle = bundle;
    bundle.attr('position', symbolMeta.bundlePosition.slice());

    if (symbolMeta.symbolRepeat) {
        createOrUpdateRepeatSymbols(bar, opt, symbolMeta);
    }
    else {
        createOrUpdateSingleSymbol(bar, opt, symbolMeta);
    }

    createOrUpdateBarRect(bar, symbolMeta, isUpdate);

    createOrUpdateClip(bar, opt, symbolMeta, isUpdate);

    bar.__pictorialShapeStr = getShapeStr(data, symbolMeta);
    bar.__pictorialSymbolMeta = symbolMeta;

    return bar;
}
Axis model
@type {module:echarts/coord/single/AxisModel}