There seems to be two three_link_pendulum.py's. Please remove the irrelevant one.

I'd suggest renaming the whole directory to "conical_pendulum" or "n_link_conical_pendulum" or "three_link_conical_pendulum".

You need to merge the two directories "three_link_pendulum" and "illustrative_example_for_viz" into this new directory to remove all redundancies.