class_docstr: Dataset for Causal Language modeling.
code: def parse_system(cfg: Any, system: str):
      # no system tokens if empty
      if system == "":
          return system
      system = f"{codecs.decode(cfg.dataset.text_system_start, 'unicode_escape')}{system}"
      if cfg.dataset.add_eos_token_to_system:
          system += cfg._tokenizer_eos_token
      return system
  
imports: import codecs
  import collections.abc
  import logging
  from typing import Any, Dict, List, Tuple, Union
  import numpy
  import pandas
  import torch
  from torch.utils.data import Dataset
  from llm_studio.src.datasets.conversation_chain_handler import ConversationChainHandler
  from llm_studio.src.datasets.text_utils import get_tokenizer
label_desc: Use image node_id 5 for calling the CustomDataset obj's underlying member method code with example usage: obj.parse_system(cfg, system) and returns: system, system