I have two clusters that are leaves/nodes from a dendrogram created with scipy.cluster.hierarchy.dendrogram. I want to find the closest common parent of the two clusters. However, I do not have the cluster indices as indicated by the dendrogram. I have only the individual points that make up each cluster. How can I find the common parent and the number of steps from each of the two clusters to that parent? (Steps meaning the number of generations between the common parent and the cluster in question).