python使用pygal报错，麻烦大家看看，帮帮忙！谢谢！

python使用pygal报错：ValueError: Invalid PI name 'b'xml''
相关代码：hist.render_to_file('1.svg')
详细错误：

希望大家帮帮忙！谢谢！

你的lxml安装有问题，重新安装一下新版本

Have you solved it?
I try to install new version of lxml,but can't work...
just like this blog say
blog.csdn.net/shuxue051/article/details/47686761

can you tell me the right way to solve it?Thanks