{"ast_node_type":"variable","tokens":[{"end":53,"kind":"keyword","start":0,"text":"let"}]}
        let a = self.memory.alloc_map.get_or(id, || {
        // So the error type is `InterpResult<'tcx, &Allocation<M::Provenance>>`.
            // We have to funnel the `InterpErrorInfo` through a `Result` to match the `get_or` API,