code: def finetune_function(
      self, pl_module: LightningModule, epoch: int, optimizer: Optimizer
  ):
      self.unfreeze_and_add_param_group(
          pl_module.layer[epoch + 1], optimizer
      )
  
imports: from collections import OrderedDict
  import pytest
  import torch
  from lightning.fabric.utilities.imports import _TORCH_GREATER_EQUAL_1_13
  from lightning.pytorch import LightningModule, Trainer, seed_everything
  from lightning.pytorch.callbacks import BackboneFinetuning, BaseFinetuning, ModelCheckpoint
  from lightning.pytorch.demos.boring_classes import BoringModel, RandomDataset
  from torch import nn
  from torch.optim import SGD, Optimizer
  from torch.utils.data import DataLoader
  from tests_pytorch.helpers.runif import RunIf
label_desc: Use image node_id 2 for calling the OnEpochLayerFinetuning obj's underlying member method code with example usage: obj.finetune_function(pl_module, epoch, optimizer) without return types