from django.utils.translation import gettext_lazy as _

from django.contrib.auth.models import User
from django.contrib.auth.validators import UnicodeUsernameValidator


class MyUnicodeUsernameValidator(UnicodeUsernameValidator):
    regex = r'^[\w.@+-\s]+\Z'
    message = _(
        'Enter a valid username. This value may contain only letters, '
        'numbers, and @/./+/-/_ characters.'
    )
    flags = 0


class User2(User):
    username_validator = MyUnicodeUsernameValidator()
    print(User.username_validator)