code: def sparsity_loss(
      X_hat_cf: torch.Tensor, X: torch.Tensor
  ) -> Dict[str, torch.Tensor]:
      """
      Default L1 sparsity loss.
  
      Parameters
      ----------
      X_hat_cf
          Auto-encoder counterfactual reconstruction.
      X
          Input instance
  
      Returns
      -------
      L1 sparsity loss.
      """
      return {"sparsity_loss": F.l1_loss(X_hat_cf, X)}
  
imports: import os
  import random
  from typing import List, Dict, Callable, Union, Optional, TYPE_CHECKING
  import numpy
  import torch
  import torch.nn
  import torch.nn.functional
  from torch.utils.data import DataLoader, Dataset
  from alibi.explainers.backends.cfrl_base import CounterfactualRLDataset
  from alibi.models.pytorch.actor_critic import Actor, Critic
label_desc: Use image node_id 5 for calling a global function with example usage: sparsity_loss(X_hat_cf, X) and returns: dict