pub fn display_dot<'a, V: PackageDotVisitor + 'g>(
        &'a self,
        visitor: V,
    ) -> impl fmt::Display + 'a {
        let node_filtered = NodeFiltered(self.graph.dep_graph(), &self.core.included);
        DotFmt::new(node_filtered, VisitorWrap::new(self.graph.0, visitor))
    }
Constructs a representation of the selected packages in `dot` format.
guppy/src/graph/resolve.rs