/// Indicates where a theme value originated.
///
/// Used to show users which values they have overridden vs. which come
/// from the base diagram.
///
/// # Variants
///
/// * `BaseDiagram`: the value comes from `InputDiagram::base()`.
/// * `UserInput`: the value was provided by the user's overlay diagram.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum ThemeValueSource {
/// Value comes from the base diagram defaults.
BaseDiagram,
/// Value was provided by the user's input diagram.
UserInput,
}