How to save modification of a file in original file not a new one?

[snippsat]

But, I want to have changes(modifications) on my original file not a new one.

I have used in-place some times,It's easy to use
When using csv module most rewriter a little so it write like writerow(csv module).
Quick test.

# -*- coding: utf-8 -*-
"""
Created on Wed Jun  2 21:02:44 2021

@author: LENOVO
"""

import csv
from in_place import InPlace

with InPlace('csv_data.csv', encoding='utf-8', backup='otherfile.csv') as revised_file:
    reader = csv.reader(revised_file, delimiter=';')
    writer = csv.writer(revised_file, delimiter=';', quoting=0)
    for idx, row in enumerate(reader, start=1):
        if idx >= 3:
            row.insert(1, row[1][0])
            row[2] = row[2][1:]
        revised_file.write(f"{';'.join(row)}\n")

This line it's not needed anymore as it was in Python 2💀

# -*- coding: utf-8 -*-