Search Directory For Filenames Containing String or Not [Python]

#!/usr/bin/python3

"""USAGE: ./find [in, not] directory string"""
#sorry this was broken earlier lol. forgot to impliment the "dirs" variable and had it running in ./ by default
import subprocess as sub
import sys

def main(innot, dirs, string):
    mylist = sub.check_output(["ls", dirs]).decode("utf-8").split("\n")
    for i in mylist:
        if innot == "in":
            if string.lower() in i.lower():
                print(i)
        else:
            if not string.lower() in i.lower():
                print(i)

if __name__ == "__main__":
    main(sys.argv[1], sys.argv[2], sys.argv[3])
    print(sys.argv[1], sys.argv[2], sys.argv[3])


"""
Mini script to quickly get coordinates to click:
#!/usr/bin/python3

import pyautogui as gui

coords = gui.position()
print(f"{coords.x}x{coords.y}")
"""