def main(cfg: InferConfig) -> float:
    """Entry point for main processing logic.

    Args:
        cfg: The inferance configuration to use.
        wer: Optional shared memory pointer for returning the WER. If not None,
            the final WER value will be written here instead of being returned.

    Returns:
        The final WER if `wer` is None, otherwise None.
    """

    yaml_str, wer_file = OmegaConf.to_yaml(cfg.decoding), get_wer_file(cfg)

    # Validates the provided configuration.
    if cfg.dataset.max_tokens is None and cfg.dataset.batch_size is None:
        cfg.dataset.max_tokens = 4000000
    if not cfg.common.cpu and not torch.cuda.is_available():
        raise ValueError("CUDA not found; set `cpu=True` to run without CUDA")

    logger.info(cfg.common_eval.path)

    with InferenceProcessor(cfg) as processor:
        for sample in processor:
            processor.process_sample(sample)

        processor.log_generation_time()

        if cfg.decoding.results_path is not None:
            processor.merge_shards()

        errs_t, leng_t = processor.total_errors, processor.total_length

        if cfg.common.cpu:
            logger.warning("Merging WER requires CUDA.")
        elif processor.data_parallel_world_size > 1:
            stats = torch.LongTensor([errs_t, leng_t]).cuda()
            dist.all_reduce(stats, op=dist.ReduceOp.SUM)
            errs_t, leng_t = stats[0].item(), stats[1].item()

        wer = errs_t * 100.0 / leng_t

        if distributed_utils.is_master(cfg.distributed_training):
            with open(wer_file, "w") as f:
                f.write(
                    (
                        f"WER: {wer}\n"
                        f"err / num_ref_words = {errs_t} / {leng_t}\n\n"
                        f"{yaml_str}"
                    )
                )

        return wer
Entry point for main processing logic.

    Args:
        cfg: The inferance configuration to use.
        wer: Optional shared memory pointer for returning the WER. If not None,
            the final WER value will be written here instead of being returned.

    Returns:
        The final WER if `wer` is None, otherwise None.
    
understand_icl/fairseq/examples/speech_recognition/new/infer.py