The teacher asks me for this code. The sorting of words in somefile using array, for, sorted(), open()

__main__.py

import sys
data = []
datalen = 0
with open(sys.argv[1],'r') as f:
    for line in f:
        for word in line.split():
        	datalen=datalen+1
        	data.insert(datalen, " "+word)
print("Array data: (NO SORTING)")
print(data)
data=sorted(data)
print("SORTED:")
print(data)
open(sys.argv[1],'r+').writelines(data)
# for execute for example: python __main__.py data.txt
# data.txt: 1 2 3 4 4 5 6 7 8 9