{"ast_node_type":"impl","tokens":[{"end":50,"kind":"keyword","start":0,"text":"impl"}]}
    impl fmt::Display for DisplayWitness<'_, '_> {
    struct DisplayWitness<'a, 'p>(&'a WitnessPat<'p>, &'a MatchCheckCtx<'p>, DisplayTarget);
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {