<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_handler_classes(self):
 """Return the list of handlers to use when receiving RPC requests."""


        handler_classes = [import_string(handler_cls) for handler_cls in settings.MODERNRPC_HANDLERS]

        if self.protocol == ALL:
            return handler_classes
        else:
            return [cls for cls in handler_classes if cls.protocol in ensure_sequence(self.protocol)]