code: def __getitem__(self, idx: int) -> Tuple[torch.Tensor, torch.Tensor]:
      # grab a chunk of (block_size + 1) characters from the data
      chunk = self.data[idx : idx + self.block_size + 1]
      # encode every character to an integer
      dix = [self.stoi[s] for s in chunk]
      x = torch.tensor(dix[:-1], dtype=torch.long)
      y = torch.tensor(dix[1:], dtype=torch.long)
      return x, y
  
file_path: tnt/examples/mingpt/char_dataset.py
imports: from dataclasses import dataclass
  from typing import Dict, Tuple
  import fsspec
  import torch
  from torch.utils.data import Dataset
label_desc: Use image node_id 3 for calling the CharDataset obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: x,  y