docstr: Update fast weights using current samples and
  return the updated fast model.
docstr_tok: ["Update","fast","weights","using","current","samples","and","return","the","updated","fast","model","."]
code: def inner_update_step(self, fast_params, x, y, t):
      """Update fast weights using current samples and
      return the updated fast model.
      """
      logits = torch.func.functional_call(
          self.model, fast_params, (x, t)
      )
      loss = self._criterion(logits, y)
  
      # Compute gradient with respect to the current fast weights
      grads = list(
          torch.autograd.grad(
              loss,
              fast_params.values(),
              retain_graph=self.second_order,
              create_graph=self.second_order,
              allow_unused=True,
          )
      )
  
      # Clip grad norms
      grads = [
          torch.clamp(
              g, min=-self.grad_clip_norm, max=self.grad_clip_norm
          )
          if g is not None
          else g
          for g in grads
      ]
  
      # New fast parameters
      new_fast_params = {
          n: param - alpha * grad if grad is not None else param
          for ((n, param), alpha, grad) in zip(
              fast_params.items(), self.alpha_params.parameters(), grads
          )
      }
  
      return new_fast_params
  
imports: from typing import Callable, List, Sequence, Optional, Union
  from packaging.version import parse
  import warnings
  import torch
  import torch
  import torch.nn
  import torch.nn.functional
  from torch.nn import Module, CrossEntropyLoss
  from torch.optim import Optimizer
  from torch import Tensor
  import math
  from copy import deepcopy
  from avalanche.training.plugins import SupervisedPlugin, EvaluationPlugin
  from avalanche.training.plugins.evaluation import default_evaluator
  from avalanche.training.templates import SupervisedMetaLearningTemplate
  from avalanche.training.storage_policy import ReservoirSamplingBuffer
label_desc: Use image node_id 4 for calling the LaMAML obj's underlying member method code with example usage: obj.inner_update_step(fast_params, x, y, t) and returns: new_fast_params