interface I {
    enum Empty {}

    /// A modification applied to either `msg.sender` or `tx.origin`. Returned by `readCallers`.
    enum CallerMode {
        /// No caller modification is currently active.
        None
    }

    /// A modification applied to either `msg.sender` or `tx.origin`. Returned by `readCallers`.
    enum CallerMode2 {
        /// No caller modification is currently active.
        None,
        /// No caller modification is currently active2.
        Some
    }

    function bar() public {}
}