pub fn query_reverse<'g, 'a>(
        &'g self,
        package_ids: impl IntoIterator<Item = &'a PackageId>,
    ) -> Result<PackageQuery<'g>, Error> {
        Ok(PackageQuery {
            graph: self,
            params: QueryParams::Reverse(self.package_ixs(package_ids)?),
        })
    }
Creates a new query that returns transitive reverse dependencies of the given packages.

Returns an error if any package IDs are unknown.
guppy/src/graph/query.rs