def METHOD_NAME(self, value):
    """Check that the username exists"""
    user = None
    try:
        user = User.objects.get(username=value)
    except User.DoesNotExist as exc:
        raise serializers.ValidationError(
            _(f"User '{value}' does not exist.")
        ) from exc
    else:
        if not user.is_active:
            raise serializers.ValidationError(_("User is not active"))
        # create user profile if missing
        try:
            profile = user.profile
        except UserProfile.DoesNotExist:
            profile = UserProfile.objects.create(user=user)
        if is_organization(profile):
            raise serializers.ValidationError(
                _(f"Cannot add org account `{user.username}` as member.")
            )
    return value