Function boot_at_declared_route 

pub fn boot_at_declared_route(defs: &[Stmt<'_>], interner: &Interner)

Boot the document at the URL the ## Page defs auto-mounts declares, so routePath() answers that URL from the page’s first statement — the page as a visitor who navigated to it finds it. A program that auto-mounts no page leaves the route where it is.