fn walk_nodes<'g>(
graph: &'g RetainedDepGraph,
starts: &FxIndexSet<&'g DepNode>,
direction: Direction,
) -> FxIndexSet<DepKind>fn walk_nodes<'g>(
graph: &'g RetainedDepGraph,
starts: &FxIndexSet<&'g DepNode>,
direction: Direction,
) -> FxIndexSet<DepKind>