Как найти строку в списке по ее началу Python?

from collections import namedtuple

User = namedtuple('User', 'id, group, name')

data = {}
with open('profiles/profiles.txt', encoding='utf-8') as f:
    for line in f:
        user_id, group, name = line.strip().split(':')
        data[int(row_id)] = User(int(user_id), group, name)


user = data[2]
print('{} состоит в группе {}'.format(user.name, user.group))