code: def calculate_metric(self):
      return self.calculate_loss()
  
imports: from typing import Dict, List
  import numpy
  import torch
  from pytext.common.constants import BatchContext, DatasetFieldName, RawExampleFieldName, Stage
  from pytext.config.component import Component, ComponentType
  from pytext.config.pytext_config import ConfigBase
  from pytext.metric_reporters.channel import Channel, ConsoleChannel
  from pytext.metrics import RealtimeMetrics
  from pytext.utils import cuda
  from pytext.utils.meter import TimeMeter
label_desc: Use image node_id 2 for calling the PureLossMetricReporter obj's underlying member method code with example usage: obj.calculate_metric() and returns: self