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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _get_stub_and_request_classes(self, service_name):
 """ import protobuf and return stub and request class """

        # Compile protobuf if needed
        codegen_dir = Path.home().joinpath(".snet", "mpe_client", "control_service")
        proto_dir   = Path(__file__).absolute().parent.joinpath("resources", "proto")
        if (not codegen_dir.joinpath("control_service_pb2.py").is_file()):
            compile_proto(proto_dir, codegen_dir, proto_file = "control_service.proto")

        stub_class, request_class, _ = import_protobuf_from_dir(codegen_dir, service_name)
        return stub_class, request_class