class_docstr: The epoch elapsed time metric.
  This plugin metric only works at training time.
  
  The elapsed time will be logged after each epoch.
class_docstr_tok: ["The","epoch","elapsed","time","metric",".","This","plugin","metric","only","works","at","training","time",".","The","elapsed","time","will","be","logged","after","each","epoch","."]
code: def before_training_epoch(self, strategy):
      super().before_training_epoch(strategy)
      self._time.update()
  
imports: import time
  from typing import TYPE_CHECKING, List
  from avalanche.evaluation import Metric, PluginMetric, GenericPluginMetric
  from avalanche.evaluation.metric_results import MetricValue, MetricResult
  from avalanche.evaluation.metric_utils import get_metric_name
  from avalanche.evaluation.metrics.mean import Mean
label_desc: Use image node_id 2 for calling the EpochTime obj's underlying member method code with example usage: obj.before_training_epoch(strategy) without return types