getNodesOnLevel

open override fun getNodesOnLevel(level: Int): HnswGraph.NodesIterator

WARN: calling this method will essentially iterate through all nodes at level 0 (even if you're not getting node at level 0), we have built some caching mechanism such that if graph is not changed only the first non-zero level call will pay the cost. So it is highly NOT recommended to call this method while the graph is still building.

NOTE: calling this method while the graph is still building is prohibited