Getting Node Ranks/Levels in Cytoscape.js Dagre Layout

Question

I am trying to add styling to cytoscape.js nodes based on their level/rank in the graph.

For example, the root node is rank 1, the children of the root node are of rank 2, and so on. Is there a function that returns the node's rank or return a collection of all the nodes with a given rank? Here is an illustration:

         Root (rank 1)
        .         .
       .            .
      .               .
   child1 (rank 2)    child2 (rank 2)

Thank you!