A minor problem with the preceding functions is that they expect us to know the node number we want to work with. A simple way to access this is by using the interactive subtreeplot() command. The subtreeplot(newick) code generates an interactive plot for the tree provided, like the one here. By clicking on particular nodes in the tree, we can get the viewer to render the subtree and print the node ID. We can then use the node ID in the functions: