code: def update(self, loss, num_samples):
      self._sum += loss
      self._num_inst += num_samples
  
imports: import logging
  import math
  from abc import ABC, abstractmethod
  from typing import Any, Dict, Optional, Tuple
  import torch
  import numpy
  from .None import constants
  from .None import utils
label_desc: Use image node_id 6 for calling the LossMetric obj's underlying member method code with example usage: obj.update(loss, num_samples) without return types