Earlier quoted context omitted.
There actually is a built in tool to generate a sequence diagram. The language is designed with the idea that it should be possible to generate such a diagram for every program. The tool to generate diagram is currently part of the vscode extension for ballerina. It's documented here. https://v1-0.ballerina.io/learn/tools-ides/vscode-plugin/gra...
The way I read the docs though, it sounded like you could generate code from a sequence diagram - generating a diagram from code isn't that new or unique (albeit, still a handy feature!)
I'm not certain it's unique, but it's pretty neat, and I can see how designing the whole language around servicing network requests would make it easier to implement / more reliably work.