@abc.abstractmethod<EOL><INDENT>def basic_auth_user(self, realm, user_name, password, environ):<DEDENT>
raise NotImplementedError<EOL>
Check request access permissions for realm/user_name/password.

        Called by http_authenticator for basic authentication requests.

        Optionally set environment variables:

            environ["wsgidav.auth.roles"] = (<role>, ...)
            environ["wsgidav.auth.permissions"] = (<perm>, ...)

        Args:
            realm (str):
            user_name (str):
            password (str):
            environ (dict):
        Returns:
            False if user is not known or not authorized
            True if user is authorized