Function implementation 

pub fn implementation() -> Value

What the implementor reports back, and the pull request body it becomes.

The body used to be one scraped SUMMARY: line under a Closes #N, which told a reviewer opening the diff cold nothing: not what was wrong, not what the change does about it, not how to check it. Asking for those separately is what puts them there, and composing the body from the fields rather than from the model’s prose is what keeps it short enough to read.