code: def forward(self, x):
      x = self.backbone(x).flatten(start_dim=1)
      z = self.projection_head(x)
      return z
  
file_path: lightly/examples/pytorch_lightning/vicreg.py
imports: import pytorch_lightning
  import torch
  import torchvision
  from torch import nn
  from lightly.loss.vicreg_loss import VICRegLoss
  from lightly.models.modules.heads import VICRegProjectionHead
  from lightly.transforms.vicreg_transform import VICRegTransform
label_desc: Use image node_id 2 for calling the VICReg obj's underlying member method code with example usage: obj.forward(x) and returns: z