syntax_data: {"ast_node_type":"other","tokens":[{"end":81,"kind":"keyword","start":0,"text":"(MaybeReachable::Unreachable,"}]}
source_snippet:             (MaybeReachable::Unreachable, MaybeReachable::Unreachable) => Ok(()),
context_before:         match (self, old) {
context_after:             (MaybeReachable::Unreachable, MaybeReachable::Reachable(set)) => {