{"ast_node_type":"other","tokens":[{"end":84,"kind":"keyword","start":0,"text":"//"}]}
        // uses its upvars (e.g. it consumes a non-copy value), but not *all* upvars
        // 2. If the coroutine-closure is forced to be `FnOnce` due to the way it
        // would force the closure to `FnOnce`.