{"ast_node_type":"other","tokens":[{"end":87,"kind":"keyword","start":0,"text":"ObligationCauseCode::MatchImpl(cause,"}]}
            ObligationCauseCode::MatchImpl(cause, _) => cause.to_constraint_category(),
        match self.code() {
            ObligationCauseCode::AscribeUserTypeProvePredicate(predicate_span) => {