class_docstr: Callback that record the mean and std of activations.
code: def layer_stats(self, idx):
      lstats = self.stats.itemgot(idx)
      return L(lstats.itemgot(o) for o in ("mean", "std", "near_zero"))
  
imports: from __future__ import annotations
  from ..basics import *
label_desc: Use image node_id 7 for calling the ActivationStats obj's underlying member method code with example usage: obj.layer_stats(idx) and returns: L