@bot.callback_query_handler(func=lambda call:True)
@bot.callback_query_handler(func=lambda call: call.data == "arg")
from telethon.tl.types import ChatParticipantCreator, ChatParticipantAdmin
for user in client.get_participants(chat, aggressive=True):
if isinstance(user.participant, ChatParticipantAdmin) or isinstance(user.participant, ChatParticipantCreator):
print(user.first_name)