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PEP 8

I would review PEP 8. Some of your style choices are not considered best practice by the Python community. Some quick observations:


Constants are given CAPS_WITH_UNDERSCORES. Not function/method parameters. PATH should be path for instance.
There is a space between the binary operators (there are, however, some exceptions: see Other Recommendations). So, for instance: indentation=4 should be indentation = 4.
Instead of if not (args.out==None):, You should do if args.out is not None: (See Programming Recommendations)
I would advise making a main function. Yes if __name__ == '__main__': is a start but I would recommend having a main function (see this answer, in particular the section "An Even Better Way"):


--

def main():        
    parser=argparse.ArgumentParser(...)
    ...

if __name__ == '__main__':
    main()