Will count all users messages of the specific group and print sorted out from most talked to none with an λ

lambda_all_participants.py

group = 'telethonchat'
print(
    (
        (
            lambda c: (
                lambda ts: "\n".join(
                    f"{t} messages from {u}" for t, u in sorted(ts, key=lambda t: -t[0])
                )
            )(
                (
                    client.get_messages(c, from_user=u).total,
                    f"{u.first_name}, {u.last_name}, {u.username or u.id}",
                )
                for u in client.iter_participants(c)
                if not u.deleted
            )
        )(group)
    ).replace(" None,", "")
)