code: def sparsity_loss(
      X_hat_cf: tf.Tensor, X: tf.Tensor
  ) -> Dict[str, tf.Tensor]:
      """
      Default L1 sparsity loss.
  
      Parameters
      ----------
      X_hat_cf
          Auto-encoder counterfactual reconstruction.
      X
          Input instance.
  
      Returns
      -------
      L1 sparsity loss.
      """
      return {"sparsity_loss": tf.reduce_mean(tf.abs(X_hat_cf - X))}
  
imports: import os
  import random
  from typing import Any, List, Dict, Callable, Union, Optional, TYPE_CHECKING
  import numpy
  import tensorflow
  import tensorflow.keras
  from alibi.explainers.backends.cfrl_base import CounterfactualRLDataset
  from alibi.models.tensorflow.actor_critic import Actor, Critic
label_desc: Use image node_id 4 for calling a global function with example usage: sparsity_loss(X_hat_cf, X) and returns: dict