How to use the forte.common.exception.ProcessFlowException function in forte

def process_one(self, *args, **kwargs) -> PackType:
        r"""Process one single data pack. This is done by only reading and
        processing the first pack in the reader.

        Args:
            kwargs: the information needed to load the data. For example, if
                :attr:`_reader` is :class:`StringReader`, this should contain a
                single piece of text in the form of a string variable. If
                :attr:`_reader` is a file reader, this can point to the file
                path.
        """
        if not self.initialized:
            raise ProcessFlowException(
                "Please call initialize before running the pipeline")

        first_pack = []

        for p in self._reader.iter(*args, **kwargs):
            first_pack.append(p)
            break

        if len(first_pack) == 1:
            results = list(self._process_packs(iter(first_pack)))
            return results[0]
        else:
            raise ValueError("Input data source contains no packs.")

#        |___________|       |_______________|     |_J1:UNPROCESSED_|
        #
        #
        # After 5th step (iteration),
        #
        #           batch_size = 2                               batch_size = 2
        # Reader -> B1 (BatchProcessor) -> P1 (PackProcessor) -> B2(BatchProcessor)
        #
        #        |___________|       |_______________|     |_______________|
        #        |___________|       |_______________|     |_______________|
        #        |___________|       |_______________|     |_______________|    --> Yield J1.pack and J2.pack
        #        |___________|       |_______________|     |_______________|
        #        |___________|       |_______________|     |_______________|

        if not self.initialized:
            raise ProcessFlowException(
                "Please call initialize before running the pipeline")

        buffer = ProcessBuffer(self, data_iter)

        if len(self.components) == 0:
            yield from data_iter
            # Write return here instead of using if..else to reduce indent.
            return

        while not self._proc_mgr.exhausted():
            # job has to be the first UNPROCESSED element
            # the status of the job now is UNPROCESSED
            unprocessed_job: ProcessJob = next(buffer)

            processor_index = self._proc_mgr.current_processor_index
            processor = self.components[processor_index]

we will have memory issues.

        Args:
            pack_id: The pack id that points to the pack to be de-referenced.

        Returns:

        """
        if pack_id not in self.pack_references:
            # This can happen when the instance is reset by the pipeline.
            return

        if self.pack_references[pack_id] < 0:
            # I am not sure if there are cases that can deduct the reference
            # count too much, but we'd put a check here just in case.
            raise ProcessFlowException(
                f"Pack reference count for pack [{pack_id}] is only "
                f"{self.pack_references[pack_id]},"
                f" which is invalid.")

        # Reduce the reference count.
        self.pack_references[pack_id] -= 1

        # If the reference count reaches 0, then we can remove the pack from
        # the pool and allow Python to garbage collect it.
        if self.pack_references[pack_id] == 0:
            self.pack_pool.pop(pack_id)

def add(self, component: PipelineComponent,
            config: Optional[Union[Config, Dict[str, Any]]] = None,
            selector: Optional[Selector] = None):
        self._processors_index[component.name] = len(self.components)

        if isinstance(component, BaseReader):
            raise ProcessFlowException("Reader need to be set via set_reader()")

        if isinstance(component, Evaluator):
            # This will ask the job to keep a copy of the gold standard.
            self.evaluator_indices.append(len(self.components))

        component.assign_manager(self._proc_mgr, self._pack_manager)
        self._components.append(component)
        self.processor_configs.append(component.make_configs(config))

        if selector is None:
            self._selectors.append(DummySelector())
        else:
            self._selectors.append(selector)