def get_bank_notification_session(self, bank_receiver=None, proxy=None):
if proxy is None:<EOL><INDENT>raise NullArgument()<EOL><DEDENT>raise Unimplemented()<EOL>
Gets the notification session for notifications pertaining to bank service changes.

        arg:    bank_receiver (osid.assessment.BankReceiver): the bank
                receiver interface
        arg:    proxy (osid.proxy.Proxy): a proxy
        return: (osid.assessment.BankNotificationSession) - a
                ``BankNotificationSession``
        raise:  NullArgument - ``bank_receiver`` or ``proxy`` is
                ``null``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_bank_notification() is
                false``
        *compliance: optional -- This method must be implemented if
        ``supports_bank_notification()`` is true.*