pub fn should_traverse(self, link: &PackageLink<'_>) -> bool {
        // NOTE: We always retain all workspace deps in the graph, otherwise
        // we'll get a disconnected graph.
        match self {
            Kind::All | Kind::ThirdParty => true,
            Kind::DirectThirdParty => link.from().in_workspace(),
            Kind::Workspace => link.from().in_workspace() && link.to().in_workspace(),
        }
    }
Returns true if this link should be traversed.
cargo-guppy/src/core.rs