{"ast_node_type":"import","tokens":[{"end":65,"kind":"keyword","start":0,"text":"///"}]}
    /// - `b` is not at offset 0, because `V` is not a 1ZST type.
    /// - For `Pair(a, b)`, `a` is always at offset 0, but may have `FieldIdx(1..)`
    /// - `a` and `b` will have a different FieldIdx, but otherwise `b`'s may be lower