usestd::fmt::Debug;/// Thermodynamic state variant.
pubtraitStateVariant: Debug {}implStateVariant forDefined{}implStateVariant forUndefined{}/// A marker that determines the _presence_ of a defined thermodynamic state.
#[derive(Debug)]pubstructDefined;/// A marker that determines the _absence_ of a defined thermodynamic state.
#[derive(Debug)]pubstructUndefined;