syntax_data: {"ast_node_type":"function","tokens":[{"end":85,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn regions(&mut self, a: I::Region, b: I::Region) -> RelateResult<I, I::Region> {
context_before:     #[instrument(skip(self), level = "trace")]
context_after:         match self.ambient_variance {