图形处理的开源类库，由AT&T实验室编写，具有很强的图像显示功能-Open-source graphics library, from the preparation of AT & T Labs, has a strong functions of image display

graphviz一定要按照安装路径安装，不能换路径。不然就不好用-it is very important to install it according to its own path

c实现的可视化工具包，实现了很多布局算法-c to achieve visualization toolkit to achieve a lot of layout algorithm

python 用的 graphviz 库，版本2.38. 安装后添加 安装路径 graphviz\bin到系统path环境变量，并重启python，否则可能报错。(Graphviz library for Python, version 2.38. Install the installation path graphviz\bin to the system path environment variable, and resta