Function ac3_from_variable 

pub fn ac3_from_variable<D: Domain>(
    var: VarId,
    variables: &mut [Variable<D>],
    constraints: &[ConstraintEnum<D>],
    adjacency: &Adjacency,
    assignment: &[Option<D::Value>],
    stats: &mut SolveStats,
    depth: usize,
) -> bool
where
    D::Value: PartialEq,

Run AC-3 propagation seeded from a single variable assignment (MAC).