pub fn to_package_query(&self, direction: DependencyDirection) -> PackageQuery<'g> {
        let package_ixs = SortedSet::new(
            self.core
                .included
                .ones()
                .map(NodeIndex::new)
                .collect::<Vec<_>>(),
        );
        self.graph.query_from_parts(package_ixs, direction)
    }
Creates a new `PackageQuery` from this set in the specified direction.

This is equivalent to constructing a query from all the `package_ids`.
guppy/src/graph/resolve.rs