* 📚 update chain method calling and 🎨 appy latest black magic
* 🔨 use black 18.4a4
* 📚 update documentation
* 📚 update English docs
* 🎨 use line length 80 for source codes
* 🎨 use line length 79 for source codes as flake8 likes it
* 🎨 minor update
* 🎨 use black 18.6b4
* Patch: 细节修正
* Add: 使用 format_code 格式化项目代码
* Update: 文档细节更新
* Docs: faq update