code: def forward(self, x):
      x = self.trunk(x)
      x = self.ln(x)
  
      x = x.mean(dim=1)  # mean over sequence len
      x = self.head(x)
      return x
  
file_path: xformers/examples/cifar_MetaFormer.py
imports: import pytorch_lightning
  import torch
  from pl_bolts.datamodules import CIFAR10DataModule
  from torch import nn
  from torchmetrics import Accuracy
  from examples.cifar_ViT import Classifier, VisionTransformer
  from xformers.factory import xFormer, xFormerConfig
  from xformers.helpers.hierarchical_configs import BasicLayerConfig, get_hierarchical_configuration
label_desc: Use image node_id 2 for calling the MetaVisionTransformer obj's underlying member method code with example usage: obj.forward(x) and returns: x