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 restart python, otherwise it may be