syntax_data: {"ast_node_type":"function","tokens":[{"end":60,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn is_const_item(&self, local: Local) -> Option<DefId> {
context_before: impl<'tcx> ConstMutationChecker<'_, 'tcx> {
context_after:         if let LocalInfo::ConstRef { def_id } = *self.body.local_decls[local].local_info() {