Insert a multiple constant value after header in csv file using python

[shantanu97]

Is it possible to insert 9 new lines of Constant Value("AA") in a CSV starting from the 2nd row? I need to insert the "AA" at the top 9 rows(after the header).

Original CSV look like this:
LEID,MI_RL,TOTDEPTH, INSERTED
07JW01,51,120,2/10/2014 10:37
DD18006,40,10,20/10/2018 16:55

Final CSV should Look like this:

LEID,MI_RL,TOTDEPTH, INSERTED
AA,AA,AA,AA
AA,AA,AA,AA
AA,AA,AA,AA
AA,AA,AA,AA
AA,AA,AA,AA
AA,AA,AA,AA
AA,AA,AA,AA
AA,AA,AA,AA
AA,AA,AA,AA
07JW01,51,120,2/10/2014 10:37
DD18006,40,10,20/10/2018 16:55

The other issue is that every CSV has a different number of columns? see another csv file has 5 columns.

OLEID,FROM,TO,ZON,PROS
07WJ05,0,125,ARCN,ABC
DDH006,891.68,7854,BASE,DEF
DD1,25687,15987,GOOD,NEM

My code:

import os
   
def prepend_multiple_lines(file_name, list_of_lines):
    # define name of temporary dummy file
    dummy_file = file_name + '.csv'
    # open given original file in read mode and dummy file in write mode
    with open(file_name, 'r') as read_obj, open(dummy_file, 'w') as write_obj:
        # Iterate over the given list of strings and write them to dummy file as lines
        for line in list_of_lines:
            write_obj.write(line + '\n')
        # Read lines from original file one by one and append them to the dummy file
        for line in read_obj:
            write_obj.write(line)
    # remove original file
    os.remove(file_name)
    # Rename dummy file as the original file
    os.rename(dummy_file, file_name)
    
def main():
    print('*** Insert multiple lines from the second position of a file ***')
    list_of_lines = ['AA','AA','AA','AA','AA','AA','AA','AA','AA'] #add 9 AA constant value
    prepend_multiple_lines("DB_1.csv", list_of_lines)
    
if __name__ == '__main__':
   main()

The code is not working??? Can anyone help what is wrong with that code.