pub fn resolve_ids<'a>(
        &self,
        package_ids: impl IntoIterator<Item = &'a PackageId>,
    ) -> Result<PackageSet, Error> {
        Ok(PackageSet {
            graph: DebugIgnore(self),
            core: ResolveCore::from_included::<IxBitSet>(self.package_ixs(package_ids)?),
        })
    }
Creates a new `PackageSet` consisting of the specified package IDs.

This does not include transitive dependencies. To do so, use the `query_` methods.

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