code: def __getitem__(self, idx):
      start_idx = idx * self.seq_len
      seq_len = min(self.seq_len, self.ntokens - 1 - start_idx)
      data = torch.as_tensor(
          self.tokens[start_idx : (start_idx + seq_len + 1)].astype(
              np.int64
          )
      )
      return data[:-1], data[1:].clone()
  
file_path: flash-attention/training/src/datamodules/datasets/lm_dataset.py
imports: import math
  import numpy
  import torch
label_desc: Use image node_id 3 for calling the LMDataset obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: data,  data