can you read and write to a file at the same time python code example

Example 1: read files and write into another files python

import sys
import glob
import os.path

list_of_files = glob.glob('/Users/Emily/Topics/*.txt') #500 files

for file_name in list_of_files:
    print(file_name)

    # This needs to be done *inside the loop*
    f= open(file_name, 'r')
    lst = []
    for line in f:
       line.strip()
       line = line.replace("\n" ,'')
       line = line.replace("//" , '')
       lst.append(line)
    f.close()

    f=open(os.path.join('/Users/Emily/UpdatedTopics',
    os.path.basename(file_name)) , 'w')

    for line in lst:
       f.write(line)
    f.close()

Example 2: python create unreadable save file

import hmac, pickle

# pickle the data
pickled = pickle.dumps(data)
digest =  hmac.new("some-shared-key", pickled, 
                   digestmod=<my choice of hasher>
                   ).hexdigest()

# now save the hashed digest and the pickled data
with open("some-file", "wb") as f:
    # save these in some way you can distinguish them when you read them
    print(digest, file=f)
    print(pickled, file=f)