How to rename a CSV file by adding MODIFIED in the filename?

[Python_User]

from tkinter.filedialog import askopenfilename
from pathlib import Path
import sys
import csv

def get_filename():
    filename = Path(askopenfilename(filetypes=[("CSV files","*.csv")]))

    return filename


def read_csv_file(filename):
    parts = list(filename.parts)


if __name__ == '__main__':              #This executes the code!
    read_csv_file(get_filename())

If I run the above code, I have the Unused variable 'parts'pylint(unused-variable) message. I do understand the parts variable is not defined, but how can it run anyway in the code Larz60 provided me? I can't find the variable parts defined in the code anyway...