syntax_data: {"ast_node_type":"function","tokens":[{"end":78,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn visit(&mut self, span: Span, value: impl TypeVisitable<TyCtxt<'tcx>>) {
context_before:     #[instrument(skip(self), ret, level = "trace")]
context_after:         self.visit_spanned(span, value);