class_docstr: The standalone disk usage metric.
  
  This metric can be used to monitor the size of a set of directories.
  e.g. This can be useful to monitor the size of a replay buffer,
docstr: Updates the disk usage statistics.
  
  :return None.
docstr_tok: ["Updates","the","disk","usage","statistics",".",":","return","None","."]
code: def update(self):
      """
      Updates the disk usage statistics.
  
      :return None.
      """
  
      dirs_size = 0.0
      for directory in self._paths_to_monitor:
          dirs_size += DiskUsage.get_dir_size(directory)
  
      self.total_usage = dirs_size
  
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 DiskUsage obj's underlying member method code with example usage: obj.update() without return types