code: def mask_tensor(x, mask, block, value=0):
      ret = x.clone()
      for h, i, j in zip(*(mask == 0).nonzero(as_tuple=True)):
          ret[
              :,
              h,
              i * block : (i + 1) * block,
              j * block : (j + 1) * block,
          ] = value
      return ret
  
file_path: triton/python/test/unit/operators/test_blocksparse.py
imports: import pytest
  import torch
  import triton
  import triton.ops
label_desc: Use image node_id 3 for calling a global function with example usage: mask_tensor(x, mask, block, value) and returns: ret