Using append for typography?

Question

Python

I have functions to save and read "database" (texter)

def save_bd(users, filename):
lines = []
for user in users:
lines.append(f'"id" : {user.id}, "mode " : "{user.mode}", "admin" : {user.admin}, "ban" : {user.ban}')
lines = '\n'.join(lines)
with open(f'{tdir( __file__)}/{filename}.txt'.replace('\\', '/').replace('vova.py/', ''), "w", encoding = 'utf-8') as file :
file.write(lines)
file.close()

def read_bd(filename):
users = []
with open(f'{tdir(__file__)}/{filename}.txt'.replace('\\', '/ ').replace('vova.py/', ''),"r", encoding = 'utf-8') as file:
lines = [x.replace('\n', '') for x in file.readlines()]
file.close()
for line in lines:
line = eval('{' + line + '}')
if line != '{}':
users.append(User(id = line['id'], mode = line["mode" ], admin = line['admin'], ban = line['ban']))
return users
This is for the VK bot. To give the same admin in a conversation, you need to change the "admin" parameter to another person to 1. I use append for this, but when I save (save_bd()), a separate line is created in the text editor. It is necessary that the first one be changed, and not a new one be created. How can this be resolved?