extension PureYAML.Parsing {
    struct ScannerFlowContext {
        var kind: ScannerFlowContextKind
        var isExpectingKey: Bool
        /// Whether an explicit key indicator (`?`) is open at this flow level, so the following scalar
        /// is the explicit key's content and must not synthesize its own implicit key. Cleared by the
        /// pair's `:` value indicator or a `,`, and discarded with the context when the collection
        /// closes, so it tracks per-level and a nested collection's `:` does not affect an outer key.
        var hasExplicitKey = false
    }
}