#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]

    pub fn new(domain: Domain) -> DecisionVariable {

        DecisionVariable { domain }

    }

    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {

        match &self.domain {

            Domain::BoolDomain => write!(f, "bool"),

            Domain::IntDomain(ranges) => {

                let mut first = true;

                for r in ranges {

                    if first {

                        first = false;

                    } else {

                        write!(f, " or ")?;

                    match r {

                        Range::Single(i) => write!(f, "{}", i)?,

                        Range::Bounded(i, j) => write!(f, "{}..{}", i, j)?,

                Ok(())

    }