code: def get_optimizer(
      model: nn.Module, lr: float = 1e-3
  ) -> torch.optim.Optimizer:
      """
      Constructs default `Adam` optimizer.
  
      Returns
      -------
      Default optimizer.
      """
      return torch.optim.Adam(model.parameters(), lr=lr)
  
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 2 for calling a global function with example usage: get_optimizer(model, lr) and returns: torch