another_namedtuples.py

from datetime import datetime
from typing import NamedTuple


class Group(NamedTuple):
    id: int
    name: str


class Client(NamedTuple):
    id: int
    group: Group
    payment_type: int
    last_authorized: datetime


def get_client_group_name(client: Client) -> str:
    return client.group.name


client = Client(
    id=1,
    group=Group(id=22, name="Постоянный покупатель"),
    payment_type=28,
    last_authorized=datetime(2017, 5, 1)
)

print(get_client_group_name(client))