code: def _baseline_matmul_with_dense_mask(
      a: torch.Tensor, b: torch.Tensor, mask: torch.Tensor
  ) -> torch.Tensor:
      res = a @ b
      res[~mask] = float("-inf")
      return res
  
imports: import pytest
  import torch
  import xformers
  import xformers.components.attention.core
  from xformers.components.attention._sputnik_sparse import _csr_to_coo
  from xformers.components.attention.core import _broadcast_batch, _create_random_sparsity, _sparse_bmm
label_desc: Use image node_id 2 for calling a global function with example usage: _baseline_matmul_with_dense_mask(a, b, mask) and returns: res