code: def make_history_mask(block):
      length = block.shape[0]
      arange = np.arange(length)
      history_mask = arange[None,] <= arange[:, None]
      history_mask = history_mask.astype(np.int64)
      return history_mask
  
file_path: megatron-lm/megatron/data/t5_dataset.py
imports: import collections
  import numpy
  import torch
  from megatron import get_tokenizer
  from megatron.data.dataset_utils import create_masked_lm_predictions, get_samples_mapping
label_desc: Use image node_id 5 for calling a global function with example usage: make_history_mask(block) and returns: history_mask