class_docstr: The average stream Disk usage metric.
  This plugin metric works only at eval time.
  
  At the end of the eval stream, this metric logs the total
  size (in KB) of all the monitored paths.
code: def __str__(self):
      return "DiskUsage_Stream"
  
imports: import os
  from pathlib import Path
  from typing import Union, Sequence, List, Optional
  from avalanche.evaluation import Metric, GenericPluginMetric
label_desc: Use image node_id 2 for calling the StreamDiskUsage obj's underlying member method code with example usage: obj.__str__() and returns: str