facilitate decoupled documentation

- [how do you test graphlib? · Issue #15 · purpleprotocol/graphlib](https://github.com/purpleprotocol/graphlib/issues/15)
- [graphlib::Graph - Rust](https://docs.rs/graphlib/0.2.0/graphlib/struct.Graph.html#method.capacity)
- [rust doc tests running - Google Search](https://www.google.com/search?q=rust+doc+tests+running)
- [Documentation tests -](https://doc.rust-lang.org/rustdoc/documentation-tests.html)
- [Documentation testing - Rust By Example](https://doc.rust-lang.org/rust-by-example/testing/doc_testing.html)
- [Tracking issue: rfc 1990 - add external doc attribute to rustc · Issue #44732 · rust-lang/rust](https://github.com/rust-lang/rust/issues/44732)
- [rfcs/1990-external-doc-attribute.md at master · rust-lang/rfcs](https://github.com/rust-lang/rfcs/blob/master/text/1990-external-doc-attribute.md)
- [rust "external_doc" - Google Search](https://www.google.com/search?q=rust+%22external_doc%22)
- [external_doc -](https://doc.rust-lang.org/unstable-book/language-features/external-doc.html)
- [Keep Rust module documentation in .md files? - Stack Overflow](https://stackoverflow.com/questions/48980028/keep-rust-module-documentation-in-md-files)
- [separate documentation from code pattern' - Google Search](https://www.google.com/search?q=separate+documentation+from+code+pattern%27)
- [What are the best documentation patterns? - Software Engineering Stack Exchange](https://softwareengineering.stackexchange.com/questions/12186/what-are-the-best-documentation-patterns)
- [c# - Separate documentation from code - Stack Overflow](https://stackoverflow.com/questions/9749472/separate-documentation-from-code)
- [rust documentation md files antipattern - Google Search](https://www.google.com/search?q=rust+documentation+md+files+antipattern)
- [inline documentation antipattern - Google Search](https://www.google.com/search?q=inline+documentation+antipattern)
- [Is code documentation an anti-pattern? - Quora](https://www.quora.com/Is-code-documentation-an-anti-pattern)
- [coding standards - Self Documenting Code Vs. Commented Code - Software Engineering Stack Exchange](https://softwareengineering.stackexchange.com/questions/51307/self-documenting-code-vs-commented-code)
- [anti patterns - "Comments are a code smell" - Software Engineering Stack Exchange](https://softwareengineering.stackexchange.com/questions/1/comments-are-a-code-smell)
- [Inline documentation, why I’m ditching it | Blog | Miller Medeiros](http://blog.millermedeiros.com/inline-docs/)
- [Writing system software: code comments. - ](http://antirez.com/news/124)
- [oop - What is the difference between loose coupling and tight coupling in the object oriented paradigm? - Stack Overflow](https://stackoverflow.com/questions/2832017/what-is-the-difference-between-loose-coupling-and-tight-coupling-in-the-object-o/37993102)
- [Coupling (computer programming) - Wikipedia](https://en.wikipedia.org/wiki/Coupling_(computer_programming))