syntax_data: {"ast_node_type":"function","tokens":[{"end":77,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn region_highlighted(&self, region: ty::Region<'tcx>) -> Option<usize> {
context_before:     /// Returns `Some(n)` with the number to use for the given region, if any.
context_after:         self.highlight_regions.iter().find_map(|h| match h {