class_docstr: Implementation of ActivationStatisticsObserver which logs the
  activation statistics to tensorboard.
class_docstr_tok: ["Implementation","of","ActivationStatisticsObserver","which","logs","the","activation","statistics","to","tensorboard","."]
code: def consume(self, stat: ActivationStatistics):
      self.writer.add_scalar(
          tag="activations/" + stat.name + "/mean",
          scalar_value=stat.mean,
          global_step=stat.iteration,
      )
      self.writer.add_scalar(
          tag="activations/" + stat.name + "/spread",
          scalar_value=stat.spread,
          global_step=stat.iteration,
      )
  
file_path: vissl/vissl/hooks/tensorboard_hook.py
imports: import logging
  import torch
  from classy_vision import tasks
  from classy_vision.generic.distributed_util import is_primary
  from classy_vision.hooks.classy_hook import ClassyHook
  from vissl.utils.activation_statistics import ActivationStatistics, ActivationStatisticsMonitor, ActivationStatisticsObserver
label_desc: Use image node_id 2 for calling the ActivationStatisticsTensorboardWatcher obj's underlying member method code with example usage: obj.consume(stat) without return types