usecrate::mark::Mark;/// A placeholder mark used for charts that have not yet been assigned a specific
/// visual type (e.g., bar, line, point).
////// This allows the "Base Chart" pattern where encodings are defined once and
/// reused across multiple layers.
#[derive(Clone, Default)]pubstructNoMark;implMark forNoMark{fnmark_type(&self)->&'staticstr{"none"}}