fil.analyze_skeletons not working in example files

[teogeo1996]

I am trying to run the example files. I have stumbled across an issue with fil.analyze skeletons. I am following the example steps exactly but when I get to the point of
fil.analyze_skeletons()
plt.imshow(fil.skeleton, origin='lower')

I get an error saying:
Traceback (most recent call last):
File "", line 1, in
File "/Users/c21094896/FilFinder/fil_finder/filfinder2D.py", line 665, in analyze_skeletons
fil.skeleton_analysis(self.image, verbose=verbose,
File "/Users/c21094896/FilFinder/fil_finder/filament.py", line 277, in skeleton_analysis
prune_graph(G, nodes, edge_list, max_path, labeled_mask,
File "/Users/c21094896/FilFinder/fil_finder/length.py", line 662, in prune_graph
G[n] = merge_nodes(node, G[n])
NameError: name 'merge_nodes' is not defined

Is there an easy fix to that?