code: def forward(self, x):
      y_hat = self.backbone(x).flatten(start_dim=1)
      y_hat = self.fc(y_hat)
      return y_hat
  
imports: import copy
  import pytorch_lightning
  import torch
  import torch.nn
  import torchvision
  from lightly.data import LightlyDataset
  from lightly.loss import NTXentLoss
  from lightly.models import ResNetGenerator
  from lightly.models.modules.heads import MoCoProjectionHead
  from lightly.models.utils import batch_shuffle, batch_unshuffle, deactivate_requires_grad, update_momentum
  from lightly.transforms import MoCoV2Transform, utils
label_desc: Use image node_id 2 for calling the Classifier obj's underlying member method code with example usage: obj.forward(x) and returns: y_hat