pub fn new(old: &'a PackageGraph, new: &'g PackageGraph) -> Self {
        Self {
            old,
            new,
            rules: RulesImpl::new(new, &DeterminatorRules::default())
                .expect("default rules should parse"),
            cargo_options: None,
            old_features_only: None,
            new_features_only: None,
            changed_paths: vec![],
        }
    }
Creates a new instance of `Determinator` with old and new package graphs.
tools/determinator/src/determinator.rs