{"ast_node_type":"other","tokens":[{"end":99,"kind":"keyword","start":0,"text":"//"}]}
        // result in the place `Downcast<Some>(*&Some(3)).0` associated to `x` and invoke `op` with
        // `Some(x)` (which matches). Recursing once more, `*&Some(3)` and the pattern `Some(x)`
        // that (where the `ref` on `x` is implied).