code: def validate_one_step(self, data):
      _, loss, metrics = self.model_fn(data)
      return loss, metrics
  
imports: import warnings
  import psutil
  import torch
  import torch.nn
  from tqdm import tqdm
  from tez import enums
  from tez.callbacks import CallbackRunner
  from tez.utils import AverageMeter
label_desc: Use image node_id 15 for calling the Model obj's underlying member method code with example usage: obj.validate_one_step(data) and returns: loss,  metrics