pub fn prop010_id_strategy(&self) -> impl Strategy<Value = &PackageId> {
        let dep_graph = &self.dep_graph;
        any::<prop::sample::Index>().prop_map(move |index| {
            let package_ix = NodeIndex::new(index.index(dep_graph.node_count()));
            &self.dep_graph[package_ix]
        })
    }
Returns a `Strategy` that generates random package IDs from this graph.

Requires the `proptest1` feature to be enabled.

## Panics

Panics if there are no packages in this `PackageGraph`.
guppy/src/graph/proptest_helpers.rs