chunk_content: lation function
  	
  A collation function is used by Trainer to gather a batch of training and evaluation examples and prepare them in a
  format that is acceptable by the underlying model.
  
  
  	Copied
  import torch
  
  
  def collate_fn(examples):
      pixel_values = torch.stack([example["pixel_values"] for example in examples])
      labels = torch.tensor([example["label"] for example in examples])
      return {"pixel_values": pixel_values, "labels": labels}
  